This qualitative study explored the knowledge, perceptions, and autonomy of 7- and 12-year-old children relative to the management of their asthma. A total of 32 children with moderate to severe asthma were interviewed using an open-ended drawing interview and a semi-structured interview. The triangulation of results from these two methods revealed developmental differences. Younger children identified medicines by shape, color, or lay terms, relied on adults to manage their asthma, and did not recognize warning symptoms of an attack. Older children mastered biomedical terminology and used medicines independently, although they sometimes asked for the assistance of an adult. All children perceived benefits and non-monetary costs of asthma medicines. However, they lacked understanding of the categories and role of asthma medicines. This study suggests that long-term control and quick-relief metered dose inhalers should be identifiable by consistent color-coding, and that professionals should tailor asthma education and information to children's stages of cognitive development.