We engage the concept of ecological instability to assess whether exposure to frequent change in multiple contexts during early childhood is associated with teacher reports of students’ overall behavior, externalizing behavior, and approach to learning during kindergarten. We operationalize multiple dimensions of children’s exposure to repeated change, including the frequency, concurrency, chronicity, timing, and type of changes children experience in a nationally-representative longitudinal cohort of U.S.-born children (Early Childhood Longitudinal Study-Birth Cohort, N~4,750). We focus on early childhood, a period when there is substantial flux in children’s family and neighborhood contexts. Predicted behavior scores differ by approximately one-fifth of a standard deviation for children who experienced high or chronic exposure to ecological change compared to those who experienced little or no change. These findings emphasize the distinctiveness of multi-domain ecological instability as a risk factor for healthy development that should be conceptualized differently from the broader concept of normative levels of change in early childhood environments.