 Importantly, even those who agree on the general nature of ST might disagree on other crucial issues. We will focus on what are typically taken to be the three most important bones of contention among Simulation Theorists: what is meant by “mental simulation”?  (section 2).  What types of simulation processes are there?  (section 3).  What is the role of mental simulation in mindreading?  (section 4).  After having considered what keeps Simulation Theorists apart, we shall move to discuss what holds them together, i.e., the opposition to the Theory-Theory of mindreading  (section 5  and  section 6).  This should give the reader a sense of the “unity amidst diversity” that characterizes ST.