System dynamics (SD) modeling is used to compare and contrast strategies for effective implementation of an evidence-based adolescent behavioral health treatment in primary care settings. With qualitative and quantitative data from an on-going cluster-randomized trial in 7 federally qualified health center sites, two implementation conditions were compared: generalist vs. specialist. In the generalist approach, the primary care provider (PCP) delivered brief intervention (BI) for substance misuse (n = 4 clinics). In the specialist approach, BIs were delivered by behavioral health counselors (BHCs) (n = 3 clinics). The resultant SD model compared ‘basecase’ dynamics to strategic approaches to deploying continuous technical assistance (TA) and performance feedback reporting (PFR). The basecase effectively represented the SBIRT intervention, which reflected actual monthly volume of adolescent primary care visits (N = 9639), screenings (N = 5937), positive screenings (N = 246), and brief interventions (BIs; N = 50) over the 20-month implementation period. Insights gained suggest that implementation outcomes are sensitive to frequency of PFR, with bimonthly events generating the most rapid and sustained screening results. Simulated trends indicated that availability of the BHC directly impacts success of the specialist model. Similarly, understanding PCPs’ perception of severity of need for intervention is key to outcomes in either condition.