By high school, parent engagement is likely to differ not only by grade, but by subject. This study surveyed students enrolled in high school science classes and found that parents of freshmen (9th graders) are more involved at home, less involved at school, and equally involved in educational planning compared to parents of high school students in higher grades. There were some differences in which background factors predicted parent engagement with freshmen and with older high school students. Overall, parent engagement contributed to students' motivation and performance in science. Controlling for background characteristics, parent engagement at home contributed to students' perceptions of their skill and their academic grades differently for ninth graders than for students in higher grades. Parent engagement at school contributed to ninth graders' valuing of what they were learning in science class but did not impact students in higher grades.