This pilot study aimed to investigate the activity participation of young adults with high-functioning autism (HFA) living in Taiwan. Eleven young adults with HFA, their caring adults, and 11 matched typically developing youth were recruited across Taiwan. The Adolescent and Young Adult Participation Sort-Taiwanese version (AYAPS-T) was administered to all three groups to compare the activity participation. In addition, youth with HFA identified activities in which they desired to participate and barriers hindering their participation. The results of this study suggest that youth with HFA had lower participation rates in activities across different domains than their typically developing peers. Youth with HFA were able to identify the activities they desired to do and the barriers hindering their participation. No significant differences in participation were found between the results reported by the caring adults and youth with HFA. Occupational therapy practitioners may work on eliminating the personal and environmental barriers that impede participation as youth with HFA transition out of secondary school.