Psychologists in the Service of the Public Act of 2007 - Amends the Public Health Service Act to require the Secretary of Health and Human Services to establish a psychology postdoctoral program to make grants to and enter into contracts with eligible individuals and institutions to encourage the provision of psychological training and services in underserved treatment areas. Requires individuals to possess a doctoral degree in psychology and to agree to provide services to a medically underserved population during the grant and at least one year thereafter. Requires institutions to use provided amounts for fellowships to such individuals.