Shifting tasks from medical staff to non-medical staff is a common practice for promoting the efficient use of healthcare resources. The aim of this study was to develop and pilot test a questionnaire that evaluates practice assistants' attitudes towards task shifting and their perceptions of the challenges of task shifting (acronym: ACD questionnaire) and to assess the psychometric properties of the questionnaire. The development and pilot testing of the questionnaire occurred from March 2016 to March 2017 and was based on guided and cognitive interviews with practice assistants. Then, an online survey was conducted throughout Germany from June to August 2017 to determine the questionnaire's psychometric properties. A factorial analysis was conducted via principal component analysis, and reliability was assessed using Cronbach's α. The questionnaire included four themes: "working conditions and job satisfaction", "confidence to execute delegated tasks", "excessive demands associated with executing delegated tasks" and "relevance of task shifting for patient care". A total of 274 practice assistants with an average age of 38.2 years participated in the online survey. Each theme included components that showed good to very good reliability (Cronbach's α 0.64-0.91). The ACD questionnaire provides a way, for the first time, to evaluate delegable tasks, including practice assistants' attitudes towards task shifting and their perceptions of the challenges generated by these tasks. The questionnaire also indicates which components of practice assistants' professional training should be intensified.