This funding opportunity announcement (FOA) encourages research grant applications to support research designed to elucidate the etiology, epidemiology, diagnosis, treatment, and optimal means of service delivery in relation to autism spectrum disorders (ASD). Basic, clinical, and applied studies are encouraged. This FOA is intended to support the broad research goals of the Strategic Plan for ASD Research (http://iacc.hhs.gov/reports/2009/iacc-strategic-plan-for-autism-spectrum-disorder-research-jan26.shtml). Mechanism of Support. This FOA will utilize the NIH Research Project Grant (R01) award mechanism and runs in parallel with two FOAs of identical scientific scope, PA-10-159 and PA-10-160, which encourage applications under the R03 and R21 mechanisms, respectively. Funds Available and Anticipated Number of Awards. Awards issued under this FOA are contingent upon the availability of funds and the submission of a sufficient number of meritorious applications.