The main purpose of this study was to develop an assessment scale for the quality of implementing learning communities in elementary schools. According to a literature review of research studies on the theory and practice of learning community, the constructs and measuring items of the assessment scale were developed. After establishing expert validity and carrying out a series of item analysis regarding the modification, selection, and confirmation of assessment items, the factor structure and items of the preliminary scale were established. A group of teachers from 42 elementary schools, which have implemented school-based learning communities for at least 3 years by the school year of 2016, participated in this study. Using data collected from 410 valid samples, exploratory factor analysis was first conducted to purify the dimensions of the questionnaire, and confirmatory factor analysis was employed to choose the most parsimonious model by comparison of the goodness of fit among competing models. Subsequently, the reliability and validity of the assessment scale were tested, the results showed that the two-level hierarchical factor structure of the scale was verified, and its goodness-of-fitness conformed to the standard. The 63 items were divided into four subscales, including principal leadership for learning, teachers’ teaching practices, parent supports, and student learning achievements. Finally, suggestions for elementary schools and future research studies were offered.