Background The Institute of Medicine recommends developing a broader workforce of mental health providers, including nontraditional providers, to expand services for older adults. Cognitive behavior therapy (CBT) is effective for late‐life generalized anxiety disorder (GAD), but no study has examined outcomes with delivery by lay providers working under the supervision of licensed providers. The current study examined the effects of CBT delivered by lay, bachelor‐level providers (BLP) relative to Ph.D.‐level expert providers (PLP), and usual care (UC) in older adults with GAD. Methods Participants were 223 older adults (mean age, 66.9 years) with GAD recruited from primary care clinics at two sites and assigned randomly to BLP (n = 76), PLP (n = 74), or UC (n = 73). Assessments occurred at baseline and 6 months. CBT in BLP and PLP included core and elective modules (3 months: skills training; 3 months: skills review) delivered in person and by telephone, according to patient choice. Results CBT in both BLP and PLP groups significantly improved GAD severity (GAD Severity Scale), anxiety (Spielberger State‐Trait Anxiety Inventory; Structured Interview Guide for the Hamilton Anxiety Scale), depression (Patient Health Questionnaire), insomnia (Insomnia Severity Index), and mental health quality of life (Short‐Form‐12), relative to UC. Response rates defined by 20% reduction from pre‐ to posttreatment in at least three of four primary outcomes were higher for study completers in BLP and PLP relative to UC (BLP: 38.5%; PLP: 40.0%; UC: 19.1%). Conclusion Lay providers, working under the supervision of licensed providers, can deliver effective CBT.