Working memory is an important component of executive functioning, an area of difficulty for many autistic children. However, executive functioning and working memory are highly malleable throughout childhood, and various student-level and environmental factors play important roles in their development. This study used the Early Childhood Longitudinal Studies--Kindergarten Class of 2011. Conditional latent growth models were constructed to identify possible predictors for autistic children's working memory performance upon entering kindergarten and their relative growth throughout their elementary school years. Study results indicate that socioeconomic status and students' approaches to learning were positively associated with autistic children's working memory performance upon school entry. Students' approaches to learning positively predicted their rate of growth during the first 3 years and negatively predicted their rate of growth during the last 3 years of elementary school. Student-teacher relationship was positively associated with the rate of growth during the last 3 years of their elementary school years. Furthermore, autistic students who started at a lower standing in working memory upon school entry were more likely to receive special education services during their elementary school years. Practical and policy implications as well as future directions are discussed.