Psychiatric disorders represent a complex, multifactorial group of conditions whose diagnostic boundaries are vague and are thought to derive from an interaction between various biological and environmental factors. These elements, taken together, underscore the difficulty in trying to elucidate their etiology, partly due to the potential limitations related to the stability, the reliability, and inherent heterogeneity of the so-defined categorical diagnoses. The level of inheritance for numerous psychiatric diagnoses varies significantly, ranging from 80% for bipolar disorder to 30% for major depressive disorder. Despite relevant contributions in understanding some of the basis for the inheritance of psychiatric diseases from the field of genetics, it is increasingly evident how only a relatively small portion of this inheritance can indeed be explained based on postulated genetic determinants of risk. Other elements, biological and environmental, potentially transmitted from one generation to the following, might be responsible for this apparent discrepancy. Epigenetic factors may represent a particularly promising avenue to study in this context as they may represent one of the many modalities for the environment to influence the inheritance of psychiatric diseases, with certain lines of evidence suggesting a possible transgenerational transmission of epigenetic changes. This element adds a further layer of complexity to consider in disentangling the complex phenomenon of inheritance for mental health disorders. In the present chapter, we will explore some of the most relevant evidence regarding the epigenetics of bipolar disorder, major depressive disorder, and schizophrenia.