Among employed adults, major depression is a leading cause of work absences (absenteeism) and impaired work performance (presenteeism) as well as short-term and long-term work disability. Depression is one of the largest and fastest growing categories of work disability claims filings in the public and private disability insurance sectors. Work loss has a range of adverse economic and human consequences for affected workers and their families, employers, insurers, and federal disability programs. In the commercially insured United States population, individuals with depression are among the costliest of all illness groups, and most of the costs of depression are directly related to employment (i.e., cost attributable to days absent from work and poor work performance). Despite advances in depression detection, diagnosis, and treatment, most adults with depression receive no care or suboptimal treatment. Research also shows that depression treatment by itself, even when it reduces symptoms, does not adequately restore work functioning. Because untreated depression results in enormous costs to companies, due to decreased performance, absenteeism, and disability, employers have reason to invest in work-based depression interventions. Indeed, for many employees and their dependents, employment provides a gateway to depression care. Care may be provided directly (e.g., an employee assistance program [EAP] offering on-site services) or indirectly (e.g., through an employer-sponsored insurance plan). We refer to these collectively as work-based depression care. Little is known, however, about the prevalence, quality, and effectiveness of these work-based interventions.