The purpose of this research was to determine if there was a correlation between earlier investment and the success of organizations providing extensive external help to enhance primary care. Analysis of 7 EvidenceNOW grantees (henceforth, Cooperatives) and the 1,720 practices researchers brought into the study using a mixed methodologies approach. Cooperatives’ level of experience before EvidenceNOW, with experience defined as a persistent track record of delivering large-scale quality improvement (QI) to primary care clinics (high, medium, or low). Implementation of external support, as measured by facilitation dose; effectiveness in enhancing clinical quality, as measured by practices’ performance on Aspirin, Blood Pressure, Cholesterol, and Smoking (ABCS); and practice capacity, as measured by the Adaptive Reserve (AR) score and the Change Process Capacity Questionnaire (CPCQ) were the dependent variables. Investigators used multivariate linear regressions and an inductive qualitative method to assess the data. High (vs. low) EvidenceNOW-participating cooperatives recruited more geographically dispersed and diverse practices, with lower baseline ABCS performance (differences ranging from 2.8% for blood pressure to 41.5% for smoking), delivered more facilitation (mean=+20.3 hours, P=.04), and improved both their QI capacity (CPCQ: +2.04, P<.001) and smoking performance (+6.43%, P=.003). Better recruitment, facilitation delivery, and outcomes could be attributed to the fact that these Cooperatives already had preexisting networks of facilitators before the launch of EvidenceNOW and leadership with experience in bolstering this workforce. Greater consistency in the delivery of facilitation support is associated with greater improvement in practice capacity and some clinical outcomes, suggesting that long-term investments in establishing regional organizations with the infrastructure and experience to support primary care practices in QI are worthwhile.