Social contexts in which confidants get to know each other affect the composition of their personal networks, inter alia the similarity among confidants. Results from analyses on a representative sample of the Dutch population between 18 and 65 years of age (SSND 2000), support the idea that differences in similarity among confidants can be explained by 1.) the social composition of a context, 2.) the extent to which interactions within a context are enforced, and 3.) the amount of time people spend in a context. Moreover, there is a certain degree of path-dependency in the use of social contexts, that leads to reinforced context effects on similarity among confidants. (Contains 8 tables and 14 notes.)