Background: Behavioural sleep problems in young children are relatively common with between 20% and 40% of those aged 1 to 5 years being affected. This paper describes the development of a simple questionnaire to assess disorders of initiating and maintaining sleep (DIMS) in children aged between 1 and 5 years for use as a selection tool for research purposes or as a screening instrument in primary care. Methods: A subsection of the Sleep Disturbance Scale for Children was adapted and piloted with a small sample of children in two inner city GP practices (n=81). Face and content validity were initially established by expert review. Discriminant validity was assessed qualitatively using interviews with mothers of identified cases and non-cases. The validity of the cut-off score was assessed by blinded case note reviews off known cases; inter-rater reliability was also calculated. Following modifications, the final questionnaire was posted to a representative sample of parents across the region with children in the appropriate age band (n = 1023). Internal reliability was assessed using Cronbach's alpha and factor analysis was undertaken to identify significant factors within the questionnaire. Results: The response rate to the population questionnaire was 61.5% (n=628) with 218 of the children having sleep scores that were indicative of DIMS (35%), echoing other figures reported in the literature. There was good internal consistency for the items (Cronbach's alpha=0.85) with two main factors accounting for 58% of the variance. Conclusion: The Tayside Children's Sleep Questionnaire (TCSQ) is an easy-to-read and reliable tool that could be used both as a clinical and research instrument to assess the severity and prevalence of DIMS in young children.