The childcare center (CCC) setting has the potential to be a strong foundation that supports the introduction of sustainable healthy lifestyle behaviors to prevent childhood obesity. It is important to assess barriers and facilitators to healthy weight development initiatives via program evaluation, including measuring CCC staff readiness to change. The overall goal of this study was to assess the readiness level over 1 school year among CCC staff who participated in "Healthy Caregivers-Healthy Children" (HC2), a cluster randomized controlled trial that evaluated the effectiveness of a childhood obesity prevention program from 2015 to 2018 in 24 low-income, racially/ethnically diverse centers. A secondary outcome was to assess how a CCC's stage of readiness to change was associated with CCC nutrition and physical activity environment, measured via the Environment and Policy Assessment and Observation (EPAO) tool. Mixed-models analysis with the CCC as the random effect assessed the impact of readiness to change over time on EPAO outcomes. Eighty-eight CCC teachers and support staff completed the HC2 readiness to change survey in August 2015 and 68 in August 2016. Only teachers and staff randomized to the treatment arm of the trial were included. Readiness to change and the EPAO. Results showed the majority of CCC staff in advanced stages of readiness to change at both time points. For every increase in readiness to change stage over 1 year (eg, precontemplation to contemplation), there was a 0.28 increase in EPAO nutrition scores (95% confidence interval [CI], 0.04-0.53; P = .02) and a 0.52 increase in PA score (95% CI, 0.09-0.95; P = .02). This analysis highlights the importance between CCC staff readiness to change and the CCC environment to support healthy weight development. Future similar efforts can include consistent support for CCC staff who may not be ready for change to support successful outcomes.