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Despite the inevitability of painful procedures in life of most children with profound intellectual disability until recently no adequate pain measures were available. The present paper describes several studies facilitating the development of an observational scale to measure pain in this specific paediatric population. First candidate items for the Kids with Intellectual Disabilities Pain Assessment Instrument for Nonverbal Signals ( KIDPAINS) were collected from both the literature and within residential institutions. In order to gain understanding of the importance of items, data were then presented to a group of nurses caring for individuals with severe and profound intellectual disabilities. As a result, good content validity of the item bank was comfirmed. Based on the results at that point, a draft scale was developed to facilitate further item development. This initial scale was checked for interpretability and applicability in a hospital enviroment. On the whole, these findings confirmed face validity. In view of the heterogeneity of the sample and its expressions, a first item selection study focussed on parental judgements on the occurrence of items. Psychometric properties of the 113 remaining items were then evaluated. Items were tested for frequency of endorsement, internal consistency, underlying componenets, coherence of dimensions and indications for construct and convergent validity. To this end, 52 children with profund intellectual and communicativ