This study aimed to predict motor coordination from a matrix of biocultural factors for 173 children (89 boys, 84 girls) aged 7–9 years who were assessed with the Körperkoordinationtest für Kinder test battery. Socioeconomic variables included built environment, area of residence, mother’s educational level, and mother’s physical activity level (using the International Physical Activity Questionnaire [short version]). The behavioral domain was marked by participation in organized sports and habitual physical activity measured by accelerometers (ActiGraph GT1M). Indicators of biological development included somatic maturation and body mass index. Among males, the best logistic regression model to explain motor coordination (Nagelkerke R2 = 50.8; χ2 = 41.166; p < .001) emerged from age-group (odds ratio [OR]: 0.007–0.065), late maturation (OR = 0.174), normal body weight status (OR = 0.116), mother’s educational level (OR = 0.129), and urban area of residence (OR = 0.236). Among girls, the best logistic regression to explain motor coordination (Nagelkerke R2 = 40.8; χ2 = 29.933; p < .01) derived from age (OR: 0.091–0.384), normal body mass index (OR = 0.142), participation in organized sport (OR = 0.121), and mother’s physical activity level (OR = 0.183). This sex-specific, ecological approach to motor coordination proficiency may help promote physical activity during prepubertal years through familiar determinants.