The authors examined science achievement growth at Grades 3, 5, and 8 and parent school involvement at the same time points using the Early Childhood Longitudinal Study-Kindergarten Class of 1998-1999. Data were analyzed using cross-classified multilevel latent growth curve modeling with time invariant and varying covariates. School-based involvement did not predict students' initial science achievement status or their growth trajectory. Gender, race/ethnicity, parent's socioeconomic status, and school's percentage of free lunch eligible students were better predictors of intercept or slope. Findings indicated that students with lower initial science achievement scores had a faster rate of growth across time. Therefore, the science achievement gap narrows over time.