Context: Over the recent years, ‘Lean Software Development’ (LSD) has been emerging as a significant practice in the Software Industry. The inherent nature of ‘Lean’ to efficiently handle frequently changing customer needs by minimizing ‘Waste’ is a major success factor in practicing it in the context of ‘Software Engineering’. In simple words, Lean Software Development is the true translation of Lean Manufacturing and Lean IT principles to Software Engineering. This work presents an in-depth analysis on the implication of lean methodologies from both ‘State of Art’ and ‘State of Practice’ in the context of Software Engineering. Objectives: The prime objective of the study is to investigate what methodologies were considered & adopted under lean philosophy and to present relevant evidence on the implication of lean methodologies in reference to what defines ‘lean’ in Software Engineering. An extensive literature review was aimed to find the existing challenging factors that negatively influenced the success of software projects and the respective lean mitigation methodologies that were employed by various software organizations to appease their negative impact. Industrial interviews were conducted by interviewing lean experts, with a motive to find the current state of lean implementation in software industry. The outcomes from the systematic literature review (State of Art) and the industry (State of Practice) are comparatively analysed to explore the similarities and differences on the state of lean implication. Finally, a set of guidelines are recommended that would benefit an Industrial Practitioner/Stakeholder/Academic Researcher in practicing the appropriate lean methodology in the context of software engineering. Methods: We conducted a ‘Systematic literature review’ (SLR) by systematically analyzing relevant studies and then interviewed industrial experts to validate our findings. The systematic literature review was conducted according to the guidelines proposed by Dr. Barbara Kitchenham stated in ‘Guidelines for performing Systematic Literature Reviews’ article. The thorough review helped us in identifying various challenging factors that negatively influenced the success of software projects and the respective lean mitigation methodologies that were practiced in the context of software engineering. The associated benefits of practicing the lean methodologies are also presented. The extensive review included peer reviewed articles from electronic databases such as IEEE Explore, Inspec, Scopus and ISI. In addition to this, we conducted snowball sampling on the references of the selected articles to avoid the potential risk of losing relevant and valuable information. Also, other potential sources of information such as books, theses/dissertations, white papers and website/blog articles are included as a part of Grey Literature. In this study, the articles related to the implication of lean methodologies in the context of software engineering were considered. The review included 72 primary studies published between 1993 and 2012. The primary studies were selected based on the following criteria: If they presented the challenging factors that negatively influenced the success of software projects. If they depicted the implication of lean mitigation methodologies (Tool/ Technique/ Method/ Process/ Practice/ Principle) that appeased the negative impact of the identified challenging factors that hampered the success of software projects. If they depicted the implication of lean methodologies (Tool/ Technique/ Method/ Process/ Practice/ Principle) in general or for a specific development/ Management/ Maintenance improvement activities that lead to the success of software projects in the context of software engineering. If they presented the benefits of practicing lean methodologies in the context of software engineering. The study quality assessment was done based on the quality criteria defined in the ‘Quality assessment criteria checklist’. The data such as Article ID, Article Title, Literature type (Peer- reviewed, Non-peer reviewed), Context of validation of the lean methodology (Industry/Academia), Subjects considered for the study (Researchers/students, Industrial practitioners), Type of article publication (Conference/ Journal/ Books/ Thesis Reports/ Doctoral dissertations/ Other), Research method used in the study (Case Study/ Experiment/ Experience Report/ Not stated/ Secondary Data Analysis/ Literature Review), Context of conducting the research (Industry/ Academia/ Not stated/ Both), Context of validation of the study (Strong/ Medium/ Weak), Publication date & year, Source of the publication, are extracted as a part of Quantitative analysis. The secondary data analysis for both ‘State of Art’ (Systematic literature review) and ‘State of Practice’ (Industry) was carried by performing a generic data analysis designed to answer our research questions. The more specific data such as the challenging factors that negatively influenced the success of software projects, the type of lean contribution presented i.e., the methodology being a Tool, Technique, Practice, Principal, Process or a Method, along with the benefits associated on their implication that helped us to answer our research questions are extracted as a part of qualitative analysis from the selected studies. The industrial interviews were conducted by interviewing potential lean experts who had decent experience in lean software development, to find the current state of lean implication in the software industry. In the end, a comparative analysis was performed to clearly understand the state of convergence and divergence between the results from extensive literature review and the industry with respect to the implication of lean methodologies in the context of software engineering. Results: A total of 72 primary articles were selected for data extraction. 56 articles were selected from the electronic databases that clearly depicted lean implementation in the context of software engineering. 9 articles were selected by conducting snowball sampling i.e. by scrutinizing the references of the selected primary studies and finally the grey literature resulted in 7 articles. Most of the articles discussed about lean implication in the context of software engineering. The depicted lean methodologies were validated in either Industry or Academia. A few articles depicted regarding lean principles and their benefits in the context of software engineering. Most of the selected articles in our study were peer- reviewed. Peer reviewing is a process of evaluating one’s work or performance by an expert in the same field in order to maintain or enhance the quality of work or performance in the particular field. This indicates that the articles considered for data extraction have been reviewed by potential experts in the research domain. Conclusions: This study provided a deeper insight into lean implication in the context of software engineering. The aim of the thesis is to find the challenging factors that negatively influenced the success of software projects. A total of 54 challenges were identified from the literature review. The 72 primary articles selected from various resources yielded 53 lean methodologies. The lean methodologies were grouped into Principles, practices, tools and methods. Mapping between the identified challenges and the mitigation lean methodologies is presented. Industrial interviews were conducted to find the current state of lean implication in software engineering. A total of 30 challenges were identified from the industry. A total of 40 lean methodologies were identified from the interviews. Comparative analysis was done to find the common challenges and mitigation lean methodologies between the State of art and State of practice. Based on the analysis a set of guidelines are presented at the end of the document. The guidelines benefit an industrial practitioner in practicing the appropriate lean methodology. Keywords: Lean Methodology, Lean software development, lean software management, lean software engineering, Systematic literature review, literature review. / Context: Over the recent years, ‘Lean Software Development’ (LSD) has been emerging as a significant practice in the Software Industry. The inherent nature of ‘Lean’ to efficiently handle frequently changing customer needs by minimizing ‘Waste’ is a major success factor in practicing it in the context of ‘Software Engineering’. In simple words, Lean Software Development is the true translation of Lean Manufacturing and Lean IT principles to Software Engineering. This work presents an in-depth analysis on the implication of lean methodologies from both ‘State of Art’ and ‘State of Practice’ in the context of Software Engineering. Objectives: The prime objective of the study is to investigate what methodologies were considered & adopted under lean philosophy and to present relevant evidence on the implication of lean methodologies in reference to what defines ‘lean’ in Software Engineering. An extensive literature review was aimed to find the existing challenging factors that negatively influenced the success of software projects and the respective lean mitigation methodologies that were employed by various software organizations to appease their negative impact. Industrial interviews were conducted by interviewing lean experts, with a motive to find the current state of lean implementation in software industry. The outcomes from the systematic literature review (State of Art) and the industry (State of Practice) are comparatively analysed to explore the similarities and differences on the state of lean implication. Finally, a set of guidelines are recommended that would benefit an Industrial Practitioner/Stakeholder/Academic Researcher in practicing the appropriate lean methodology in the context of software engineering. Methods: We conducted a ‘Systematic literature review’ (SLR) by systematically analyzing relevant studies and then interviewed industrial experts to validate our findings. The systematic literature review was conducted according to the guidelines proposed by Dr. Barbara Kitchenham stated in ‘Guidelines for performing Systematic Literature Reviews’ article. The thorough review helped us in identifying various challenging factors that negatively influenced the success of software projects and the respective lean mitigation methodologies that were practiced in the context of software engineering. The associated benefits of practicing the lean methodologies are also presented. The extensive review included peer reviewed articles from electronic databases such as IEEE Explore, Inspec, Scopus and ISI. In addition to this, we conducted snowball sampling on the references of the selected articles to avoid the potential risk of losing relevant and valuable information. Also, other potential sources of information such as books, theses/dissertations, white papers and website/blog articles are included as a part of Grey Literature. In this study, the articles related to the implication of lean methodologies in the context of software engineering were considered. The review included 72 primary studies published between 1993 and 2012. The primary studies were selected based on the following criteria: If they presented the challenging factors that negatively influenced the success of software projects. If they depicted the implication of lean mitigation methodologies (Tool/ Technique/ Method/ Process/ Practice/ Principle) that appeased the negative impact of the identified challenging factors that hampered the success of software projects. If they depicted the implication of lean methodologies (Tool/ Technique/ Method/ Process/ Practice/ Principle) in general or for a specific development/ Management/ Maintenance improvement activities that lead to the success of software projects in the context of software engineering. If they presented the benefits of practicing lean methodologies in the context of software engineering. The study quality assessment was done based on the quality criteria defined in the ‘Quality assessment criteria checklist’. The data such as Article ID, Article Title, Literature type (Peer- reviewed, Non-peer reviewed), Context of validation of the lean methodology (Industry/Academia), Subjects considered for the study (Researchers/students, Industrial practitioners), Type of article publication (Conference/ Journal/ Books/ Thesis Reports/ Doctoral dissertations/ Other), Research method used in the study (Case Study/ Experiment/ Experience Report/ Not stated/ Secondary Data Analysis/ Literature Review), Context of conducting the research (Industry/ Academia/ Not stated/ Both), Context of validation of the study (Strong/ Medium/ Weak), Publication date & year, Source of the publication, are extracted as a part of Quantitative analysis. The secondary data analysis for both ‘State of Art’ (Systematic literature review) and ‘State of Practice’ (Industry) was carried by performing a generic data analysis designed to answer our research questions. The more specific data such as the challenging factors that negatively influenced the success of software projects, the type of lean contribution presented i.e., the methodology being a Tool, Technique, Practice, Principal, Process or a Method, along with the benefits associated on their implication that helped us to answer our research questions are extracted as a part of qualitative analysis from the selected studies. The industrial interviews were conducted by interviewing potential lean experts who had decent experience in lean software development, to find the current state of lean implication in the software industry. In the end, a comparative analysis was performed to clearly understand the state of convergence and divergence between the results from extensive literature review and the industry with respect to the implication of lean methodologies in the context of software engineering. Results: A total of 72 primary articles were selected for data extraction. 56 articles were selected from the electronic databases that clearly depicted lean implementation in the context of software engineering. 9 articles were selected by conducting snowball sampling i.e. by scrutinizing the references of the selected primary studies and finally the grey literature resulted in 7 articles. Most of the articles discussed about lean implication in the context of software engineering. The depicted lean methodologies were validated in either Industry or Academia. A few articles depicted regarding lean principles and their benefits in the context of software engineering. Most of the selected articles in our study were peer- reviewed. Peer reviewing is a process of evaluating one’s work or performance by an expert in the same field in order to maintain or enhance the quality of work or performance in the particular field. This indicates that the articles considered for data extraction have been reviewed by potential experts in the research domain. Conclusions: This study provided a deeper insight into lean implication in the context of software engineering. The aim of the thesis is to find the challenging factors that negatively influenced the success of software projects. A total of 54 challenges were identified from the literature review. The 72 primary articles selected from various resources yielded 53 lean methodologies. The lean methodologies were grouped into Principles, practices, tools and methods. Mapping between the identified challenges and the mitigation lean methodologies is presented. Industrial interviews were conducted to find the current state of lean implication in software engineering. A total of 30 challenges were identified from the industry. A total of 40 lean methodologies were identified from the interviews. Comparative analysis was done to find the common challenges and mitigation lean methodologies between the State of art and State of practice. Based on the analysis a set of guidelines are presented at the end of the document. The guidelines benefit an industrial practitioner in practicing the appropriate lean methodology. Keywords: Lean Methodology, Lean software development, lean software management, lean software engineering, Systematic literature review, literature review. / 0091-8375920473