One of the most common concerns for parents is their child’s sleep behaviour. Inadequate sleep can impact cognitive, behavioural and social-emotional functioning. There are predictable developmental changes that occur in sleep behaviour. It is important to know that sleep problems throughout childhood and adolescence are common and that there is a spectrum from sleep problems through to diagnosed sleep disorders. This chapter starts with a brief overview of what sleep is, how it is regulated, steps for assessment and theoretical underpinnings that aid in further understanding treatment principles for behaviourally based sleep problems (e.g., cognitive and behavioural theories and the 4-P model). Then a developmental framework is used to outline common behaviourally based sleep problems experienced across developmental stages and the range of family-based behavioural interventions that can be applied from infancy through to adolescence. Throughout the chapter, the impact of behaviourally based sleep problems on the family is considered. Finally, the role of the therapist in working with children experiencing behaviourally based sleep problems and the importance of implementing a core competencies approach are discussed.