The attention given to the Randstad Holland as a key concept in urban and regional development strategies of the Dutch national government has come in waves over decades. This chapter presents a selection of some of the most important studies that have been exploring functional coherence in the Randstad at different points in time, culminating in an overview table in which their main characteristics. It discusses the studies from a conceptual and methodological perspective. The chapter considers general conceptual and methodological requirements that need to be adhered to when studying functional coherence in polycentric metropolitan areas such as the Randstad. The Netherlands became a unified state in 1815, but resembled the former federation of provinces until the start of industrialisation. The political landscape has become fragmented and populist parties have risen to prominence, particularly those on the right of the political spectrum. Researchers addressing functional coherence in the Randstad have drawn attention to the issues of multiplexity and individual-level heterogeneity.