Few studies have explored the association between neighborhood characteristics and adherence to diabetes self-management behaviors, and none have examined the influence of neighborhood safety on adherence to treatment regimens among patients with diabetes. To assess whether neighborhood safety is associated with self-reports of technical quality of care and with nonadherence to diabetes treatment regimens. A cross-sectional analysis of a population-based sample of California adults responding to the 2007 California Health Interview Survey. Multivariable logistic regression models were used to examine the association of self-reported neighborhood safety with technical quality of care and treatment nonadherence, adjusted for sociodemographic characteristics, barriers to access to care, and health status. Adults with type 2 diabetes currently receiving medical treatment. Patient-reported neighborhood safety, performance of recommended processes of care by provider, treatment nonadherence (patient delays in filling prescriptions and obtaining needed medical care). Self-reported neighborhood safety was not associated with process measures of technical quality of care, but was associated with treatment nonadherence. Specifically, compared to those who report living in a safe neighborhood, a higher proportion of patients living in unsafe neighborhoods reported delays in filling a prescription for any reason (21.9% vs. 12.8%, aOR = 1.69, 95%CI 1.19, 2.40) and delays in filling a prescription due to cost (12.2% vs. 6.8%, aOR = 1.63, 95%CI 1.02, 2.62). Contextual factors, such as neighborhood safety, may contribute to treatment nonadherence in daily life, even when the technical quality of care delivered in the clinic is not diminished.