ABSTRACTObjectives:Older people describe positive and negative age-related changes, but we do not know much about what contributes to make them aware of these changes. We used content analysis to categorize participants’ written comments and explored the extent to which the identified categories mapped onto theoretical conceptualizations of influences on awareness of age-related change (AARC).Design:Cross-sectional observational study.Participants:The study sample comprised 609 UK individuals aged 50 years or over (mean (SD) age = 67.9 (7.6) years), enrolled in the PROTECT study.Measurements:Between January and March 2019, participants provided demographic information, completed a questionnaire assessing awareness of age-related change (AARC-10 SF), and responded to an open-ended question asking them to comment on their responses.Results:While some of the emerging categories were in line with the existing conceptual framework of AARC (e.g. experiencing negative changes and attitudes toward aging), others were novel (e.g. engagement in purposeful activities or in activities that distract from age-related thoughts). Analysis revealed some of the thought processes involved in selecting responses to the questionnaire items, demonstrating different ways in which people make sense of specific items.Conclusions:Results support the ability of the AARC questionnaire to capture perceived age-related changes in cognitive functioning, physical and mental health, and engagement in social activities and in healthy and adaptive behaviors. However, findings also suggest ways of enriching the theoretical conceptualization of how AARC develops and offer insights into interpretation of responses to measures of AARC.