This study analyzes data of the Educational Longitudinal Study of 2002 to examine the association between parental provision of task-extrinsic rewards for academic performance, parent involvement in students' learning, and students' choice of study field in college. Results show that frequent receipt of task-extrinsic rewards for good grades from parents lowers students' probability of selecting STEM major in college by up to 12 percentage points compared to never or rarely receiving such rewards from parents. Results also show that this association is only statistically significant for high frequency of parental external rewards, and moderate frequency does not exert similar effect. The lowered likelihood of STEM enrollment for students frequently exposed to parental task-extrinsic rewards adds to the evidence that external rewards could have adverse effect on students that lasts into college.