This article considers the role of diverse institutions in framing adult learning systems. The focus is on institutional characteristics and configurations in different countries and their potential impact on the extent of adult learning, as well as on inequalities in access to adult learning. Typologies of education and training systems as well as labour market and welfare systems are introduced in relation to specific particularities relevant to adult learning. An emphasis is placed on how institutions that are interwoven into several systems are relevant to adult learning. This is then considered and elaborated in the context of post-Socialist countries in order to highlight important nuances that are relevant to adult learning and skill formation systems. (Contains 5 notes and 3 tables.)