The purpose of this study is to determine the extent to which Project TEAM (Teens making Environment and Activity Modifications) is an effective, socially valid, and feasible intervention that prepares youth with developmental disabilities ages 14-21 to respond to environmental barriers and increases participation in school, work, and the community. Project TEAM is a manualized intervention co- facilitated by a disability advocate and a licensed professional. The intervention includes eight group sessions and two experiential learning field trips. In addition, young adults with disabilities serve as peer mentors on field trips and contact youth weekly to support attainment of goals. Project TEAM outcomes are to: increase youths' knowledge of environmental factors and modification strategies; reduce the impact of environmental barriers on participation; increase self-efficacy and self-determination; and increase participation in a personal activity goal in the area of education, employment, or community life. This project builds on a participatory action research partnership with disability community stakeholders to address the following research questions: (1) To what extent do youth with disabilities participating in Project TEAM achieve intervention outcomes? (2) What are the characteristics of youth with disabilities who most benefit from Project TEAM? (3) To what extent are goals, procedures, and outcomes of Project TEAM important and acceptable (socially valid) to youth with disabilities?.