This project extends the work of a previous Head Start-University Partnership grant by developing an extensive manual for a brief, small group intervention protocol, the Circle of Security (COS). The COS is a 20-week intervention focusing on strengthening child-parent attachment security. In addition, this project will empirically test whether the COS protocol can be successfully taught to, and implemented on-site by, supervised, community-based service providers (i.e., community mental health center [CMHC] staff working in partnership with Head Start/Early Head Start [HS/EHS] staff). Researchers will complete 1-year post-intervention follow-up assessments for a group of child-parent dyads who participated in the initial partnership grant. In addition, researchers will complete a "Beta-version" manual for the COS protocol, including extensive coverage of the intervention protocol and a collection of the most commonly used intervention goals and individualized intervention plans developed during the initial partnership grant. During the second and third years of the study, researchers will recruit a sample of 44 HS/EHS child-parent dyads for participation in the COS intervention. Researchers will determine the degree of success of the protocol as implemented by trained CMHC staff and the HS/EHS center staff through measuring the changes in pre- and post-intervention assessments, and then comparing these changes to the changes found during the initial partnership grant. During the final year of the study, researchers will complete a final version of the COS protocol manual based on verbal and written feedback from the trained CMHC and HS/EHS staff as well as feedback from the supervision process. In addition, researchers will develop a dissemination plan for the manual and write a set of suggested procedures for creating similar HS/EHS - CMHC partnerships in other communities.