Transition age youth with disabilities are at an elevated risk to experience depression and anxiety compared to youth without disabilities. The current study evaluates the implementation feasibility, acceptability, and potential efficacy of the "Think, Be, Do" curriculum (a mental health curriculum) for transition age students in special education classrooms. The "Think, Be, Do" curriculum is a teacher delivered, ten-session mental health curriculum, based in cognitive behavioral and ecological theory, that promotes behavior activation and cognitive reframing of negative thoughts. A total of 11 classrooms were recruited and 115 students participated in a randomized controlled trial. Classrooms were randomly assigned to either treatment (n = 7) or control condition (n = 4). Treatment condition classrooms were exposed to the "Think, Be, Do" curriculum twice a week for five weeks. Control condition classrooms were instructed to continue business as usual. Results from the pre-post feasibility trial indicate that the "Think, Be, Do" curriculum was feasible to implement with high fidelity, and was acceptable to the teachers who implemented the curriculum and for student participants. In addition, student knowledge increased on common mental health concerns (e.g., depression and anxiety) for participants in the treatment condition. There were no clinically meaningful differences found between conditions on the putative mechanisms (e.g., behavior activation, negative thoughts), internalizing and externalizing symptoms, and academic competence. Implications for research and practice are discussed, including the need for further curriculum adaptation, development of reliable and valid mental health measures, and the need for a more targeted implementation approach. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]