Although adolescents often seem to improve in their functioning during residential care, there still is little knowledge on what factors are important in achieving these changes. The present study aims to identify the care factors that are important for adolescents’ behavior change during secure residential care. We conducted in-depth interviews with eight adolescents, their parents, eight group care workers and seven teachers concerning their in-care experiences. Both adolescents and parents commonly attributed changes during secure residential care to the treatment environment. Group care workers and teachers did not have a clear, consistent view on the treatment aspects causing positive change with the adolescents. According to the adolescents, good professionals apply a fine balance between rules and freedom, show empathy and are available for support. The view of parents corresponds to this image. Although group care workers are perceived as available for support, adolescents tend to make little use of this help if they experience personal problems during care. The results highlight the importance of responsiveness of secure residential care professionals to the needs and perspectives of adolescents and parents.