Although progress has been made in developing and disseminating evidence-based treatments for most forms of mental illness, there are still huge gaps in our knowledge base. Coverage of serious mental illness with adequate and disseminable intervention strategies is all too limited. Hence, there is a great need for the next generation of clinical scientists to contribute to the mission of treatment development for mental illness. In this course we will learn about, and critique, treatment development models. We will review the steps in treatment development spanning from the study of mechanisms on to proof of concept and to establishing the feasibility of novel treatment ideas.