Higher education research, while a specialist and late developing field, has reached a level of maturity such that researchers have recently been endeavouring to summarize and synthesize what has been learnt. This article identifies and analyses many of the systematic reviews and meta-analyses of areas or aspects of higher education research that have been carried out. It demonstrates the breadth and depth of higher education research, charting how much we have learnt, what the particular foci of attention have been, and suggests -- by the absence of analysis -- which areas may need more attention.