Diagnosis of rare, genetic diseases is challenging, but conceptual frameworks of the diagnostic process can be used to guide benchmarking and process improvement initiatives. Using the National Academy of Medicine diagnostic framework, we assessed the extent of, and reasons for, diagnostic delays and errors in schwannomatosis, a neurogenetic syndrome characterized by nerve sheath tumors and chronic pain. We reviewed the medical records of 97 patients with confirmed or probable schwannomatosis seen in two U.S. tertiary care clinics from 2005-2016. Survival analysis revealed a median time from first symptom to diagnosis of 16.7 years (95% CI, 7.5-26.0 years) and median time from first medical consultation to diagnosis of 9.8 years (95% CI, 3.5-16.2 years). Factors associated with longer times to diagnosis included initial signs/symptoms that were intermittent, non-specific, or occurred at younger ages (p<0.05). Thirty-six percent of patients experienced a misdiagnosis of underlying genetic condition (18.6%), pain etiology (16.5%) and/or tumor imaging/pathology (11.3%). One-fifth (19.6%) of patients had a clear missed opportunity for appropriate workup that could have led to an earlier schwannomatosis diagnosis. These results suggest that interventions in clinician education, genetic testing availability, expert review of pathology findings, and automatic triggers for genetics referrals may improve diagnosis in schwannomatosis.