This study examined the prevalence and patterns of sleep problems in a sample of children with anxiety disorders. Participants were 175 children, aged 6 to 18 years, with a primary diagnosis of generalized anxiety disorder, separation anxiety disorder, social phobia, or obsessive-compulsive disorder, presenting for assessment at an anxiety specialty clinic. Ninety percent of the sample demonstrated at least one sleep-related problem (SRP), and 82% experienced two or more. Frequencies of sleep problems did not differ between males and females or across younger and older children. However, type of sleep problems varied by diagnostic category. Findings also revealed strong associations between SRPs and a range of child anxiety measures, as well as a predictive relationship whereby number of anxiety disorders predicted number of sleep problems. Results highlight the high co-occurrence of sleep and anxiety problems, emphasizing the need for assessment and intervention efforts targeting sleep disturbance in this population.