Effective social support from teachers, peers, and guardians is a key to promoting students' study wellbeing at school. However, little longitudinal research has examined the implications of distinctive combinations of social support for students' study wellbeing. To address this limitation, we measured multiple dimensions of school-related social support (teacher, peer, and guardian support), study engagement, and study-related burnout in a sample of 1,545 Finnish lower secondary school students in Grades 7, 8, and 9 (age 13, girls 51%). Latent transition analyses identified a six-profile solution for each wave of data and revealed substantial inequality in perceived social support. First, we found four profiles where social support from all three sources was experienced either on high, moderate, low, or very low level labeled as "strong support" (33%), "moderate support" (43%), "low support" (13%), and "exceptionally low support" (3%), respectively. In addition, two "mixed profiles" were found, where a low level of social support from one source was combined with moderate levels of social support from two other sources. These two profiles were labeled as "adult support" (5%) and "low teacher support" (3%) profiles. The social support profiles differed from each other in terms of study engagement and study-related burnout, suggesting that social support from specific sources has a somewhat different effect on features of students' study wellbeing. Moreover, the results showed that the experiences of school-related social support and study wellbeing are prone to change, highlighting the importance of each source of support throughout the students' school path.