This study determined the knowledge, attitude, and practices (KAP) of parents and children on waste segregation and if the parents’ KAP influence the children’s KAP. Fifty-six pupils at a preschool laboratory were administered a pictorial interview schedule. The parents accomplished a self-administered questionnaire. The correlation coefficients were generated to determine relationships between children’s age and sex to their KAP and parents’ KAP and children’s KAP. Regression analysis was done to determine parents’ and children’s KA contribution to their P. Findings show that majority of the parents and nearly half of the children have high KAP scores. As children’s age increases, their KAP slightly increases. Girls have slightly higher KAP than boys. For parents, knowledge was a predictor of practice while for children, attitude was a predictor for practice. There is a weak positive relationship between children’s and parents’ KAP. Parents’ P is also the biggest contributor to the children’s KAP. The family is an influential agent for children’s sustainable development practices.