This chapter engages with existing literature and case studies to examine current challenges and ways forward for the sustainability assessment of urban agriculture. It identifies current conceptualisations of urban agriculture, and sustainability assessment methods, and discusses them in the light of normative, systemic, and procedural dimensions of sustainability assessment. The diversity of urban agriculture and its presence in different urban contexts worldwide, represent challenges for sustainability assessment. This chapter shows that there is a paucity of assessment methods that are both specifically developed for urban agriculture and flexible enough to be applicable for different forms of urban agriculture in the Global North and South. Sustainability assessment of agriculture has usually focused on agriculture for market production in relatively stable rural contexts. However, urban agriculture poses challenges of diversity, multi-functionality, contested framings, and knowledge integration, which manifest more acutely in urban than in rural contexts, and which many existing sustainability assessment approaches and methods fail to address. The chapter discusses opportunities to move the practice of sustainability assessment of urban agriculture forward. These include the adoption of inter- and transdisciplinary research strategies, and a critical and reflexive approach to urban agriculture practices, power relations, social norms, and institutional conditions.