Cerebral small vessel disease (SVD) is among the most frequent causes of both stroke and dementia. There is a growing list of genes known to be implicated in Mendelian forms of SVD. Also, genome-wide association studies have identified common variants at a number of genetic loci that are associated with manifestations of SVD, among them loci for white matter hyperintensities, small vessel stroke, and deep intracerebral hemorrhage. Driven by these discoveries and new animal models substantial progress has been made in elucidating the molecular, cellular, and physiologic mechanisms underlying SVD. A major theme emerging from these studies is the extracellular matrix (ECM). Recent findings include a role of structural constituents of the ECM such as type IV collagens in hereditary and sporadic SVD, the sequestration of proteins with a known role in ECM maintenance into aggregates of NOTCH3, and altered signaling through molecules known to interact with the ECM. Here, we review recent progress in the identification of genes involved in SVD and discuss mechanistic concepts with a particular focus on the ECM.