While sustained academic and community partnerships can improve relationships between research partners, they could also influence study outcomes. Research on this issue is limited. We conducted a trial (2010-15) to test two implementation strategies for an evidence-based intervention to promote colorectal cancer (CRC) screening at community organizations in Los Angeles (N = 17). For both strategies, trained community health advisors (CHAs) recruited Filipino Americans (N = 673) who were non-adherent to CRC screening guidelines. The main study outcome was CRC screening status of participants at 6-month follow-up. This case study compares outcomes among organizations that had participated in our prior effectiveness trial and new organizations with which we had no prior relationship. Using multilevel logistic regression with multiple imputation for missing outcomes, we compared CRC screening rates among previous versus new partners controlling for study condition and organizational, CHA and participant characteristics. Screening rates were substantially higher among participants of previous versus new partner organizations in unadjusted analysis (77% versus 55%, OR 2.8, p = 0.12), after adjusting for organization-level variables (81% versus 42%, OR 7.5, 95% CI [2.0-28.7], p = 0.003) and after additionally adding CHA and participant level factors to the model (79% versus 47%, OR 5.9, CI [1.3-27.3], p = 0.02). Analyses using complete cases and assuming not-screened for missing outcomes indicated similar differences in screening rates (30 and 33 percentage points, respectively). Study outcomes that are achieved with long-term community partners may not be generalizable to new partners. However, inclusion of new community partners is important for external validity of dissemination efforts in community settings. NCT01351220 (ClinicalTrials.gov).