Wellness Enhancing Physical Activity for Young Children (WE PLAY) is a teacher training that is based online and was designed to support early childhood educators' efforts to promote physical activity (PA) through structured and unstructured active play with preschoolers. WE PLAY includes six components: (1) online training; (2) video library; (3) game sheets; (4) teacher self-assessment; (5) supervisor support; and (6) activity packs that are designed to work synergistically. The purpose of this study was to examine the impact of WE PLAY on children's levels of moderate to vigorous physical activity (MVPA) during school hours. We hypothesized that children whose teachers received WE PLAY would have higher levels of MVPA during school hours at post-intervention relative to pre-intervention and relative to children whose teachers did not receive WE PLAY. A second purpose was to examine the impact of WE PLAY on teacher outcomes (i.e., knowledge, intentions, perceived behavior control, subjective norms, perceived power beliefs, normative beliefs, and moral norms). We hypothesized that teachers who participated in WE PLAY would demonstrate higher scores on each of these variables at post-intervention relative to pre-intervention and to teachers in the control group. A cluster randomized controlled trial was used in this study. Six Head Start preschools were pair matched and randomized to the intervention (WE PLAY) or control groups. Preschool children (N=57) and their teachers (N=25) participated. Child MVPA was measured using accelerometers for 5-day periods at pre- and post-intervention. Teacher variables were measured using online surveys.

Inclusion Criteria:

• All teachers at the participating programs, and all children within the participating teachers' classrooms, were eligible to participate in this study.

Exclusion Criteria:

• There were no exclusion criteria based on gender, race/ethnicity, language spoken at home, socio-economic level, or any other demographic variable.