Single checking medications has been increasingly adopted over the past decade by nurses in Australian healthcare services. However, attitudes toward the practice of only one nurse checking medications remain unclear. The aim of this article is to report on the development, reliability, and validity of a tool to measure nurses' attitudes to single checking medications in a health service in which single checking has been in place for over a decade.In a cross-sectional survey design, the Single Checking and Administration of Medications Scale (SCAMS-II) was used to measure the attitudes of 299 registered nurses (RNs) who were single checking medications in one metropolitan teaching hospital in Australia. Exploratory factor analysis was used to explore the dimensions that best represented the SCAMS-II. Cronbach's α was used to assess internal consistency of the identified subscales. To test the construct validity of the emergent questionnaire, Confirmatory Factor Analysis and Rasch analyses were performed.The psychometric properties of the SCAMS-II revealed 12 items with three reliable subscales: a five-item accountability model; a four-item efficiency model; and a three-item knowledge model.In settings where single checking is current practice, the SCAMS-II is recommended as a reliable tool to measure nurses' attitudes toward the single checking of medications. The findings from this study may assist healthcare organizations in the development of policy and procedure guidelines for the safe administration of medications.