This portfolio thesis consists of three parts: a systematic literature review, an empirical paper and a set of related appendices. The thesis as a whole considers what gratitude means and how it is experienced by individuals living with a diagnosis of a chronic condition. The first section is a systematic literature review that explores how gratitude is experienced by individuals living with a diagnosis of cancer, and critically examines how gratitude as a concept is understood and discussed within the cancer literature. Eighteen papers were reviewed. The data were synthesised using a meta-ethnographic approach, which took a critical interpretivist stance to consider how findings were structured and interpreted by researchers. The findings indicate that people living with cancer encounter positive experiences related to gratitude, which have multiple aspects, and co-occur with difficult experiences. The findings are discussed within the context of wider literature, and the implications for future gratitude research are considered. The second section of the portfolio is an empirical study that explores the meaning of the concept of gratitude for people who are living with dementia in the community, and the experience of this concept. A secondary aim of the study was to explore the usability and acceptability of a diary as a data collection method for this group. The research used a mixed-methods approach, primarily collecting qualitative data using interviews and diaries, and analysing this using Interpretative Phenomenological Analysis. Secondary quantitative data were collected via a questionnaire and summarized using descriptive statistics to assess the usability of the diary method. Eight participants aged over 65 and living in the community were interviewed, and six of these participants kept a gratitude diary for a week following interview. Two superordinate themes and seven subthemes emerged from the data. These findings indicate that gratitude has meaning as a multidimensional construct and is experienced in life with dementia, influenced by and balanced with the changes of dementia and ageing. Descriptive statistics indicate that a diary may be an acceptable method of data collection for this group. The findings are discussed in the context of wider literature, and the implications for dementia care generally and the specific application of positive psychology interventions are discussed. The third section consists of a set of appendices relating to both the systematic literature review and the empirical paper. Also contained within these appendices are a reflective statement and an epistemological statement, which consider the researcher’s experience of conducting the research and the philosophical position and assumptions underlying the research.