This thesis investigates decision-making activities leading to the initial selection of which new ideas should be selected for further development or rejected. This process, often referred to as idea screening, is described as being one of the most important, but also challenging, tasks to master during the entire innovation process. There are two main reasons for this: Firstly, not all ideas are good and secondly no firm has the resources to develop every single idea proposed to it. Thus, it is important to be careful when initially deciding which ideas are to be selected and developed into future possible innovations in order to eliminate weak ideas and retain those that have a substantial chance of becoming successful.  Two alternative decision-making approaches are explored in the thesis (the intuitive and rational approaches). In the thesis, the concept of intuition during the screening of product and service ideas is demystified. The empirical findings show that decision-makers utilize five main underlying criteria when intuitively assessing ideas. Of these, the findings indicate user-value to be the most important one, or at least the criterion that most assessors emphasize when making intuitive decisions. The findings presented in the thesis increase our understanding of the use of rational and holistic intuitive decision-making when screening ideas during the Front End Innovation phase, as well as questioning the traditional view of intuition, as a decision-making tool that is only reliable if applied by those with a vast amount of experience and expertise. The reported findings indicate that, for example, users with an understanding of the idea context are able to intuitively identify the ideas that decision-making experts identify as the top (best) ones. Hence, managers faced with a situation where they are being inundated with new ideas can turn to non-experts for help. / This thesis explores and investigates two alternative decision-making approaches (the intuitive and the rational approaches) used when screening ideas during the initial part of the innovation process. In this thesis, the concept of intuition when screening product and service ideas is demystified. The empirical findings show that decision-makers utilize five main underlying criteria when making intuitive assessments of ideas. Of these, the findings indicate that user-value is the most important one, or at least the single criterion that most assessors emphasize when making an intuitive decision. The findings presented in the thesis increase our understanding of the use of rational and holistic intuitive decision-making when screening ideas during the Front End Innovation phase, as well as questioning the traditional view of intuition, as a decision-making tool that is only reliable if applied by those with a vast amount of experience and expertise. The reported findings indicate that, for example, users with an understanding of the idea context are able to intuitively identify the ideas that decision-making experts identify as the top (best) ones. Hence, managers faced with a situation where they are being inundated with new ideas can turn to non-experts for help.