Much work on infrastructure in the sociology of markets has built on Michel Callon’s analysis of market agencements. Infrastructures and agencements are seen to share several qualities – they are sociomaterial hybrids, emerge out of ongoing practice, and format the character and agency of people and things in the market. These commonalities have allowed Callonian and infrastructural perspectives to develop in concert, but also delayed engagement with their differences. This chapter begins such an engagement, arguing that the concept of infrastructure highlights a pragmatically and phenomenologically important boundary elided in the Callonian perspective between components of an agencement that are physically and cognitively present to actors and those which – though critical to action – are not. Situating this boundary in a theoretical perspective on market agencements has two benefits. First, it highlights a distinct mode of “infrastructural power” stemming from asymmetric relations of dependency and discretion across infrastructural and noninfrastructural components of agencements; second, it draws attention to the underappreciated role of flexible “boundary objects” in bridging these components and holding together market agencements despite their conflicting elements. On the basis of these, the chapter suggests refinements of the Callonian perspective on the alignment of framings and the framing/overflowing dialectic within markets.