Students' out-of-school science participation has been identified as a factor that supports adaptive science outcomes. Researchers have largely investigated students' out-of-school science participation in terms of structured science activities (e.g., attending a science camp), with far less consideration of how students' involvement in unstructured out-of-school science activities (e.g., using at-home science kits) may also be associated with students' aspirations and achievement in science. Research in this area has established a conceptual framework by which activities can be categorized by the activity's level of interaction (i.e., whether receptive or active). Although this conceptual framework is useful to understand the types of unstructured activities in which students engage, this research has tended to overlook the fact that students often participate in more than one out-of-school unstructured activity. The present investigation addressed this dearth of research by examining the extent to which different typologies of student participation in out-of-school receptive and active unstructured activities existed. The study also examined if these profiles were uniquely associated with students' aspirations and achievement in science above and beyond the effects of their current level of in-school participation. The study employed a latent class analysis of N = 996 Australian high school students (40.60% girls) from six schools serving predominately above average socioeconomic status Australian high school students. Four distinct profiles of out-of-school participation in unstructured activities were found: Optimal, Receptive, Active, and Minimal Out-of-School Participation (OSP). The Optimal OSP and Receptive OSP profiles were associated with the higher aspirations (beyond students' in-school participation), and both were significantly higher than the Active OSP and Minimal OSP profiles. Students' in-school participation was most strongly associated with students' achievement. These findings suggest that encouraging students' participation in unstructured activities, especially receptive unstructured activities, and their in-school participation may be viable avenues by which to improve students' science aspirations and achievement.