California community colleges have a completion crisis problem, with over 70% of students failing to graduate. This study was conducted to identify effective support services in the Extended Opportunity Programs and Services (EOPS) program, which serves marginalized community college students. This EOPS program study surveyed almost 2,000 EOPS students, who are served in 14 community colleges in the Los Angeles region, to explore effective support services that lead to positive retention and completion outcomes. The study had three phases: (a) the review of retention data of EOPS students in the Los Angeles Community College District (LACCD), (b) the EOPS student survey, and (c) the EOPS staff survey. The study revealed that the most used EOPS support services by students were (a) EOPS counseling, (b) book vouchers/grants, (c) student educational planning, and (d) priority registration. Student respondents revealed the most impactful EOPS support services were (a) book vouchers/grants, (b) EOPS counseling, (c) cash grants, (d) student educational planning, and (e) priority registration. Similarly, the EOPS staff ranked the most impactful support services as (a) EOPS counseling, (b) book vouchers/grants, and (c) priority registration. The services least used by respondents were (a) foster youth support, (b) the Cooperative Resources Agencies for Education (CARE) program for single parents, and (c) graduation assistance. The least impactful services ranked by the EOPS staff were (a) foster youth support services, (b) gift cards, and (c) graduation assistance. These results indicate that staff hold similar views to their students of the top EOPS services. Such similarity in ranking also indicates that students share with the program's staff an understanding of what is most impactful and where they believe resources should be most effectively directed. The study also reviewed retention rates of EOPS students versus non-EOPS students at all nine colleges in LACCD, and revealed that EOPS students' retention rates were over 20% higher than non-EOPS students. These results indicate that EOPS is operating effectively to improve retention rates for participants. The intent of this study was to identify effective support services in the EOPS program to determine which services students used and valued, to identify which services EOPS staff thought were helpful, and to examine retention and completion rates systemwide. After reviewing and analyzing the data, the evaluation showed that the study's objectives had been achieved. [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/en-US/products/dissertations/individuals.shtml.]