This chapter frames comparative and global policy studies on adult education as an intelligible area of research, and presents a meta-investigation that, without claiming to be exhaustive, enables researchers to reflect on and interpret what connects existing studies, and identify possible gaps. It does so on a corpus of 58 academic texts produced and/or in circulation in the Global North, for the most articles in peer-reviewed journals and, to a lesser extent, books and book chapters, published in 2000-2015; in short, this meta-investigation led to the identification of four research patterns, each based on a combination of the main unit of analysis and particular research scope. By pinpointing at their strengths and limitations, the author argues for the need to cherish these diverse patterns and the necessity of scrutinising closely the type of knowledge they produce.