This thesis investigates the distinction, or distinctions, between response-dependent and response-independent concepts or subject matters. I present and discuss the three most influential versions of the distinction: Crispin Wright’s, Mark Johnston’s, and Philip Pettit’s. I argue that the versions do not compete for a single job, but that they can supplement each other, and that a system of different distinctions is more useful than a single distinction. I distinguish two main paradigms of response-dependence: response-dependence of subject matter (Johnston and Wright), and response-dependence of concepts only (Pettit). I develop Pettit’s ‘ethocentric’ story of concept acquisition into an account of concept evolution that suggests answers to a range of hard questions about language, reality, and the relation between them. I argue that while response-dependence theses of subject matter can be motivated in very different ways, the resulting theses are less different than they might seem. I suggest that the traditional ways of distinguishing response-dependent subject matters from response-independent ones – in terms of a priori biconditionals connecting facts of the disputed class with responses in subjects in favourable conditions, and fulfilling some further conditions such as non-triviality and sometimes necessity – may not be the best approach. I also discuss two general problems for response-dependence theses: the problem of ‘finkish’ counterexamples, and the problem of specifying the ‘favourable conditions’ a priori, yet in a non-trivial way. The discussion of response-dependence is informed by a framework based on the idea that some realism disputes can be viewed as location disputes: disputes over the correct location of the disputed properties among several levels of candidate properties. The approach taken in this work is a charitable one: I try to make sense of response-dependence. The conclusion is the correspondingly optimistic one that the idea(s) of response-dependence makes sense.