Age-Friendly Community Initiatives (AFCIs) have gained recognition as essential responses to the needs of aging populations. Despite their growing significance, there is a notable lack of effective measurement tools to assess the planning, implementation, and sustainability of AFCIs. The purpose of this study was to develop and validate a survey tool for evaluating AFCIs. A sequential exploratory mixed-method design was used in two phases. First, we identified key themes from interviews with AFCI leads to generate AFCI survey items and regional workshops. Then, we conducted a pilot of the survey and assessed its measurement properties. Thematic analysis of interviews with 68 key informants from 58 AFCIs revealed four main themes: AFCI priorities, enablers, challenges, and benefits. These themes, combined with feedback from AFCI stakeholders at the regional workshops and a AFCI conference, informed the development and refinement of a reliable and valid AFCI survey in 2019, supported by a high Cronbach's Alpha value (α = 0.881). Steps were identified to maintain and sustain the AFCI survey over time. The survey accommodates AFCIs' diverse demographics, governance structures, and priorities with a standardized and flexible approach for effective measurement. This research contributes to the academic understanding of AFCIs and aids community leaders and policymakers in planning, implementing, and evaluating AFCIs.