The different lysosomal storage disorders (LSDs) manifest with a wide spectrum of clinical presentations. Most of these disorders are typically diagnosed early in life, due to the severity of the associated phenotypes. However, it is important to appreciate that some of the LSDs present later in adolescence or adulthood. The diverse findings triggering the initial diagnosis, as well as the range of manifestations arising later during the disease course, contribute to the complexity of these issues. Clinical presentations occurring at a more advanced age, especially psychiatric and behavioral manifestations, can be overlooked or misdiagnosed. This review describes different psychiatric and behavioral manifestations encountered in individuals with LSDs, including psychosis, schizophrenia, mood disorders, aggressiveness, early-onset dementia, and conduct disorder. Twelve different disorders are presented, including descriptions of their associated biochemical abnormalities, clinical presentations, pathology, epidemiology, and genetics. In addition, discussions of neurocognitive, behavioral, and psychiatric findings are outlined for each disorder. A greater awareness of these features may help to reduce missed diagnoses, to avoid unnecessary, invasive and expensive testing, and to facilitate an earlier detection of these rare disorders. Earlier diagnosis can enable the implementation of appropriate interventions and improve genetic counseling.