Translating evidence-based research into practice requires data from clinical trials in real world settings. This paper presents "lessons learned" from the implementation of an RCT of breastfeeding promotion interventions at two busy, urban, prenatal care sites. Data were obtained via direct observations, qualitative interviews, and study statistics. Primary challenges include: time and space burdens, "research vs. service" mission conflict, and the provider learning curve for conducting interventions. Primary facilitators include: researcher presence for enhancing rapport with participants and staff, site staff labeling of both the research interview and intervention as "value added time," and the ability of research staff to assist the clinic beyond the scope of the clinical trial. Specific suggestions are given for building collaborative bonds between the research team, clinicians, administrators, and staff in busy urban practices.