This study examined the effects of science and engineering (S & E) inquiry on preschool and kindergarten children's academic outcomes using a randomized control-group design. Participants were divided into three groups: a classroom-only group (C-only) receiving NGSS-aligned S & E inquiry; a classroom plus family engagement group (C + F) with additional family S & E activities; and a control group with standard instruction. Intervention teachers received two weeks of summer professional development (PD) and ongoing coaching to enhance their S & E knowledge and pedagogical skills. The C + F group's families received science activity packs and invitations to science events. Academic abilities were assessed for preschoolers using the Early Learning Scale (ELS) and for kindergartners using the Kindergarten Early Learning Scale (KELS). Results indicated that both intervention groups in the preschool cohort, and the C + F group in the kindergarten cohort, outperformed the control group. No significant differences were found between the two intervention groups in either cohort. Findings highlight the importance of continuing to explore the contribution of both in-school and home S & E exposure. Future research implications are discussed.