Underachievement has usually been explained through a mix of individual and environmental factors, though these are often treated as separate influences rather than as an integrated whole. This chapter reframes underachievement as the emergent outcome of a dynamic learner–environment system that has ceased to function adaptively. Drawing on the Actiotope Model of Giftedness, we show how restrictive participation patterns, misaligned goals, depleted or misallocated resources, and weakened regulation can disrupt developmental progress. Accordingly, diagnosis and intervention aim at restoring systemic functionality rather than correcting the individual. While the framework is illustrated through classroom cases, its logic applies broadly. Ultimately, underachievement arises when the learner–environment relationship no longer sustains development.