This document summarizes a study on defining and measuring the middle class in South Africa. It begins by noting the lack of clarity in existing research due to different definitions of class. It then proposes a new vulnerability-based approach to define the middle class using panel data from the National Income Dynamics Study. Specifically, it estimates the risk of falling into poverty over six years based on initial household conditions. A risk of 10% is used to set the lower bound for the middle class, and virtual invulnerability to poverty sets the upper bound. The estimated expenditure ranges for the South African middle class are R3,104 to R10,387 per capita monthly. Applying this methodology, the study finds that the middle class makes up about