The objective of this study is to assess the impact of inflammatory arthritis on young adults' activity participation using quantitative and qualitative methods to advance the field's conceptualization of functional status. Young adults diagnosed with juvenile idiopathic arthritis or rheumatoid arthritis completed (1) the Health Assessment Questionnaire-Disability Index to determine functional status and (2) the day reconstruction method to explore experiential dimensions of function, including functional performance, functional satisfaction, and severity of arthritis symptoms during activities on the previous day. Bivariate analyses were conducted to examine relationships between functional status, experiential variables, and demographic variables. Open-ended questions were provided for participants to report ways that arthritis affected their participation that were not otherwise reflected within survey questions; responses were numerically coded using summative content analysis. Among 37 participants (24.8 ± 3.3 years old), 70% reported moderate-to-severe disability. On average, participants experienced pain, stiffness, or fatigue for more than 50% of their waking hours. Functional status significantly correlated with functional performance (r = - 0.39, p = 0.02) and satisfaction (r = - 0.39, p = 0.02), yet did not correlate with stiffness or fatigue severity or duration of symptoms throughout the day. Participants described strategies that improved their ability to participate in certain activities but reduced their overall quality of activity engagement and caused emotional distress. Young adults with arthritis may experience more significant functional limitations than previously reported. Traditional measures of functional assessment may not capture experiential components of activity that affect participation, such as severity of stiffness or fatigue or the duration of symptoms throughout the day.