This study explores middle school students' aspirations in science, technology, engineering, and medical (STE-M) careers by analyzing survey data during their eighth and ninth grade years from an ethnically and economically diverse sample of Southern California urban and suburban public school students (n = 493). Students were classified based on their responses to questions about their science ability beliefs and subjective task values using latent class analysis (LCA). Four distinct groups of students were identified: "Science is Me"; "I Value Science But Don't Do It Well"; "I Can Do Science but I Don't Value It Highly"; and "Science is Not Me." Few students (22%) were classified as having strong science ability beliefs, and only a third as strongly valuing learning/doing science; a majority (57%) were in the Science is Not Me category, underscoring the scope of the challenge to invite more young people to want to learn science. As predicted, students who believed they could do science and valued science were more likely than others to indicate interest in STE-M careers. This relationship between perceptions and aspirations was true regardless of gender, ethnicity, and type of STE-M field, but varied depending on socioeconomic status. Using LCA to organize information about students' science self-perceptions may help target specific interventions to student interests and aspirations and better support and encourage their persistence in STE-M careers.