This study explores the relationship between parental motivational practices, Children’s mathematics achievement trajectories, and persistence in science, technology, engineering, and mathematics (STEM) careers. Nationally representative longitudinal survey data were analyzed using latent growth curve analysis. Findings indicate that parents’ motivational practices influence their children’s mathematics achievement in terms of where the Children start in the 7th grade and how much mathematics achievement grows or changes through the 12th grade. Findings also indicate a positive relationship between mathematics-specific, intrinsically focused parental motivational practices and growth in mathematics achievement and persistence in STEM careers. These findings provide specific information about how different types of parental motivational practices influence long-term mathematics achievement and persistence in STEM careers.