The aim of this study was to test a training and technical assistance program in early care and education (ECE) center-based programs focused on obesity prevention – Healthy Way to Grow (HWTG). After completing a self-assessment, ECE programs develop actionable policies to improve the wellness environment. Then, they receive individualized one-on-one support from a local, trained Child Care Specialist to develop, implement, and monitor policies. Three hundred and sixty ECE programs participated in HWTG for at least one year. Center-level outcomes were examined pre- and post-intervention, including the number of policies, wellness educational opportunities offered (to staff, families, and children), and monitoring wellness practices. A subset of centers was followed for five years to determine if the program results were sustained over time. Study findings revealed that after participating in HWTG for one year, centers developed more policies, provided more educational opportunities, and more frequently monitored wellness practices at ECE centers. Even with reduced training and technical assistance in years two through five of the program, centers were able to maintain gains in improvements to wellness environments. These findings provide evidence for the effectiveness of the HWTG wellness program and offer insights into how to support ECE programs to improve wellness environments. (author abstract)