Purpose: This study examined the prevalence, predictors, and patterns of mechanical restraint in an inpatient dual diagnosis population. Design and Methods: Data were longitudinally collected from patients affected by severe mental illness and comorbid substance abuse that were hospitalized in three large wards from 2006 to 2012. Findings: In a sample of 1698 hospitalizations, the use of mechanical restraint ranged between 1% and 4% per year. The diagnosis of schizophrenia (odds ratio [OR], 2.64; 95% confidence interval [CI], 1.29-5.40), the use of stimulant substances (OR, 5.68; 95% CI, 2.78-11.59) and male sex (OR, 3.22; 95% CI, 1.12-9.27) were associated with an increased risk of being exposed to mechanical restraint. Practice Implications: Specialized interventions targeting people at risk of mechanical restraint may further reduce the incidence of restraint and improve treatment outcomes.