This chapter looks at the connections of valuation and platforms and maintains that valuation can be understood as a distinct feature of digital sociality. It starts with introducing a conceptual distinction between valuation platforms both in the broader and the narrower sense. The main part of the chapter describes how valuation plays a crucial role for platforms. The two platforms Airbnb and Spotify serve as examples to deal with three observations and related questions: (1) Platforms have disrupted markets and become an important sector of global economies. What are the main economic characteristics and effects of valuation related to platforms? (2) Platforms have been conceptualized as evaluative infrastructures that structure user interaction. What does this mean for questions of power and control? (3) Platforms foster social change and tend to redefine established orders of worth. How do platforms contribute to value conflicts? The chapter concludes with a brief summary, an outlook on current developments and a call for further research.