This systematic review examines Asynchronous Online Discussions (AODs) in higher education, with a specific focus on AOD increasing learning outcomes and AOD alternatives. Inclusion and exclusion criteria were used to search academic databases and Google Scholar to find 35 peer-reviewed articles. An overview of the research context is provided before examining the themes that emerge in the literature. Constant Comparison was used to identify key themes such as interaction and participation, AOD format, group size, tools and strategies, and AOD alternatives. The results indicate that despite their widespread acceptance and use, there is very little consensus on best practices for AODs and almost no research into AOD alternatives. This review concludes with suggestions for future research into this important area.