Complexity is one of the major demands of adolescents' future life as adults. To investigate adolescents' competence development in applying problem-solving strategies in complex environments, we conducted a 2-wave longitudinal study in a sample of Finnish adolescents (11-17 years old; N = 1,959 at Time 1 and N = 1,690 at Time 2, 3 years later). In this study, we aimed to: (a) determine the optimal number of strategy use profiles while solving complex problems, (b) determine the number of meaningful developmental paths for each profile, and (c) test the impact of reasoning abilities and learning-related motivational beliefs on the probability that an adolescent with a given strategy use profile will take a given developmental path. Using latent transition analysis, we found 4 meaningful strategy use profiles: "Proficient Explorers," "Rapid Learners," "Emerging Explorers," and "Low-Performing Explorers." Forty-three percent of the participants were classified as having the same strategy use profile in Time 1 and Time 2. The strategy use of 34% was assessed as having improved between Time 1 and Time 2, while that of 21% was assessed as having declined between Time 1 and Time 2. Verbal reasoning ability and learning-related motivational beliefs predicted whether the developmental path of "Emerging Explorers'" was more likely to remain stable, improve, or decline over time.