Participation in occupations is considered essential for individuals' health and wellbeing. Participation is a multidimensional construct that encompasses objective and subjective dimensions that transform over the course of life. Nonetheless, there is a lack of comprehensive measures that examine young adults' participation in age-appropriate activities. Therefore, we developed the Young Adults' Daily Participation Scale (YADAPS) and aimed to explore its psychometric properties. In Study 1, the content validity of the YADAPS was established based on nine experts. Its internal consistency, criterion, convergent, and construct validity were explored among 115 typical young adults (21-35 years). Using a different sample, Study 2 examined YADAPS discriminant validity among 33 young adults with developmental coordination disorder (DCD) and 52 typical peers. No consumer and community involvement was included in these studies. The relevance of YADAPS items was sufficient. Internal consistency was acceptable to excellent in most scales (.74 ≤α≤ .89). Criterion validity was supported by correlations between the subjective participation scales and a wellbeing measure. Convergent validity was found for all scales. No gender effect was observed (p≥ .05). However, significant differences (p≤ .05) were found between individuals with and without DCD. The YADAPS appears to be a promising measure of objective and subjective dimensions of participation in young adults. The results support the importance of examining various participation dimensions, including occupational experience. Thus, it may be used for clinical purposes among young adults as well as for occupational science research, to broaden our understanding on the interplay between participation dimensions in various life situations in young adulthood. However, further research is needed on psychometric properties, the most suited scoring method, and to consolidate their robustness among diverse populations of young adults. Participation, or how one engages in daily life activities, greatly affects wellbeing. The activities in one's routine change over the lifespan, in accordance with one's developmental phase. Existing assessments of participation have limitations, like not considering young adults' concerns or only focussing on certain aspects of participation. By focussing on both the objective-observable and subjective-experiential aspects of participation, the Young Adults' Daily Participation Scale (YADAPS) strives to be a comprehensive assessment tool designed specifically for reflecting activities relevant in young adulthood. This manuscript provides preliminary validity and reliability for the YADAPS, a new questionnaire that assesses objective and subjective aspects of participation in activities relevant for individuals in young adulthood. Furthermore, the questionnaire is able to distinguish between young adults with and without participation difficulties; therefore, it is suitable for research and clinical use.