Objectives To understand the process by which early childhood education (ECE) providers effectively used an existing intervention to facilitate the creation or strengthening of a written breastfeeding policy, understand the factors important to this process, and present a logic model to guide future intervention design and evaluation. Methods A purposive sample of interviewees who recently completed an ECE nutrition and physical activity intervention and reported positive pre-post scores for breastfeeding support were recruited to complete semi-structured interviews. Interviews were recorded, transcribed, and coded, following a Grounded Theory approach. Results The ECE programs (n = 23) had a written breastfeeding policy and were located across six states in the United States. The most common aspects of breastfeeding support covered in the policies were handling and storing of breastmilk, pieces of equipment to be provided (e.g., breast pump), and the creation of a space or room designated for breastfeeding and pumping. Many factors important to the policy creation process were identified such as motivation, education, technical assistance, perceptions of parental indifference, staff buy-in, and time and administrative constraints. Once motivated to create a policy, ECE providers described actions, such as gathering background information and model policies, discussing policy needs with stakeholders, utilizing technical assistance, and overcoming barriers. Conclusions for Practice From these findings, a logic model was created to guide future intervention design and evaluation, and several recommendations were made to help guide subsequent interventions in promoting the development and implementation of written breastfeeding policies at ECE programs.