The few studies about whether parents’ implicit theories about ability (ITs) predict their children’s academic success and relevant parental behavior have produced mixed results. In response, research suggested that parents’ ITs might be more important in contexts that make children’s intellectual potential salient. Therefore, we investigated the role of parents’ ITs in such a situation: After fourth grade in Bavaria, Germany, students are tracked into one of three secondary school types (one university-track and two non-university-track) depending on their grades (in mathematics, German, and basic science). First, we examined if parents’ ITs predicted whether their children achieved the required grade average for a university-track school (that requires the highest grades). Second, because not all parents whose children achieved this threshold sent them to university-track schools, we investigated among the parents whose children had achieved the university-track threshold grade average whether parents’ ITs predict their track choice. Participants were 578 fourth-graders and their parents. Parents’ educational level was controlled for in all analyses. As expected, children of parents with a more incremental theory were more likely to achieve the university-track threshold grade average. For those children who achieved that threshold, parents with a more incremental theory were more likely to actually send their children to university-track schools. This effect was moderated by grade average. These results suggest that parents’ ITs may indeed be more important in contexts that make children’s intellectual potential salient, such as tracking decisions—especially if children’s achievement raises even slight doubts about whether they will succeed.