To what degree, if at all, does suffering from a mental illness reduce one’s freedom? Jean-Paul Sartre stated that “Mental illness is the way out a free organism, in its total unity, invents in order to live in an unlivable situation.” In this paper, I critically evaluate Sartre’s conception of mental illness, examining its implications for practical freedom and ontological freedom. Sartre’s argument that mental illness results from an “unlivable situation” indicates that external factors are the causes of these conditions. However, his rejection of the positivist psychiatry model neglects to consider the complexities of mental health issues, which include a combination of biological, environmental, psychological, and genetic factors. This evaluation contends that mental illness itself reduces one’s practical freedom via its choice-inhibiting symptoms, constraining the sufferer’s ability to shape the essence of her being. Furthermore, I argue that, in accordance with Sartre’s conception of mental illness, mental health issues are perpetuated by various societal conditions which worsen the sufferer’s symptoms by limiting her practical freedom within her external reality. Additionally, this evaluation critiques Sartre’s rejection of mental illness as the result of genetic conditions. I assert that genetic predispositions to mental illness indicate a factor of predetermination––a philosophy that is incompatible with Sartre’s definition of ontological freedom. Hence, I challenge the validity of Sartre’s famous claim that “existence precedes essence” (1975). This paper also posits a proportional relationship between ontological freedom and responsibility, demonstrating how a reduction in ontological freedom necessitates a corresponding reduction in a mentally ill individual’s moral responsibility. Finally, I propose an addendum to Sartre’s contention that all individuals are condemned to be free: because ontological freedom comes in varying degrees, all individuals are not equally condemned to be free.