Incorporating citizen participation into urban planning is a continued struggle; more recently, this has been coupled with a push to enhance the sustainability of urban developments. Various sustainability certification schemes aim to help developers build to high sustainability standards, yet few have incorporated strong citizen participation requirements alongside. BREEAM Communities is one of the first to do so. This dissertation aims to utilise Chantry’s (2022) political spaces of citizen engagement heuristic to assess the efficacy of such citizen engagement requirements in the BREEAM Communities framework. Findings from eight BREEAM Communities Assessors unveiled that the framework facilitates mixed levels of citizen engagement. In the realms of proposal formation and proposal implementation, BREEAM Communities has stringent requirements that have the potential to facilitate high-quality engagement. However, the information provision and deliberation aspects of engagement were found to be poorly facilitated. This research therefore recommends including specific information provision and deliberation stipulations in the BREEAM Communities compliance notes. Chantry’s (2022) heuristic was also evaluated; it was found that stakeholder attitudes to engagement could not be represented on the heuristic, yet it is important in influencing citizen engagement quality. Equally, a new political space of engagement timing was discovered. This, alongside smaller adjustments, has been added to an enhanced political spaces of citizen engagement heuristic. Findings concerning both BREEAM Communities and Chantry’s (2022) heuristic can provide a productive foundation to push for more effective citizen participation, both in theory and in practice.