Posttraumatic stress disorder (PTSD) is a debilitating condition that results from the experience of a traumatic event. Natural kinds are mind-independent entities found in nature and are the objects of scientific inquiry. It is common to deny that PTSD is a natural kind, but extant denials assume a thesis of natural kinds that can be called “essentialism”. According to essentialism, many entities are not natural kinds that one would expect should be natural kinds. The homeostatic cluster view of natural kinds offers an alternative that accommodates these cases, including, superficially, the claim that PTSD is a natural kind. I introduce two novel objections to this claim and recommend a distinction aimed to resolve the newly introduced problems.