Breastfeeding is now widely recognized as a vital obesity prevention strategy and hospitals play a primary role in promoting, supporting and helping mothers to initiate and maintain breastfeeding. The Baby-Friendly Hospital Initiative (BFHI) provides an evidence-based model that hospitals can use to plan and implement breastfeeding quality improvement (QI) projects. Funding under Communities Putting Prevention to Work (CPPW), administered by the CDC, brought together key Chicago partners to provide individualized support and technical assistance with breastfeeding QI projects to the 19 maternity hospitals in Chicago. A community organizing approach was taken to mobilize hospital interest in breastfeeding QI projects, leading to successes, e.g. 12/19 (63 %) Chicago hospitals registered with Baby-Friendly USA, Inc. (BFUSA) to pursue official Baby-Friendly designation. Key factors that fostered this success included: involving all levels of hospital staff, financial incentives, and ongoing tailored technical assistance. To assist other communities in similar work, this article discusses the approach the project took to mobilize hospitals to improve breastfeeding support practices based on the BFHI, as well as successes and lessons learned.