Adult education is a key component of worldwide collaborative efforts to achieve social justice aims, such as the UN's Sustainable Development Goals. Such collaborative efforts require the involvement of all sectors, including non-governmental organisations (NGOs). In particular, given the prevalence of globalising and neoliberal influences on development, NGOs providing adult education programmes must navigate complex political and financial hurdles in addition to cultural differences. To evolve our understanding of the role NGOs and their efforts play in international development education, this systematic literature review investigates adult education programmes of NGOs operating in Non-Western contexts. Findings indicate programmes require stakeholder commitment to social justice, concerted efforts to adapt to social and economic contexts, and intentional cultivation of local and international partnerships. While findings align with a general understanding of effective practices within different cultural contexts, this synthesis of empirical work provides a foundation for deeper understanding of how to implement such culturally relevant practices and improve the path forward for NGO adult education programmes and partnerships.