Environments where children move about provide affordances that play a significant role in their development. This research presents the Affordances for Motor Behavior of Schoolchildren assessment tool, which aims to assess the interdependent systems, such as home, school, and sports activities, that can influence 6- to 10-year-old children's motor development, motor learning, and motor competence. After establishing face validity, 259 south Brazilian families completed the questionnaire. We assessed construct validity on the whole sample with confirmatory factor analysis. The model testing showed a very good fit, and the structural model presented significative loading coefficients from the identified variables to the theoretically specified latent variables (factors). Significant correlation values were found between factors: home and materials (r = 0.77), home and school (r = 0.41), and materials and school (r = 0.56). Our results suggest that the Affordances for Motor Behavior of Schoolchildren can assess the opportunities for action provided to children by their home, the materials in it, and their school.