Few older adults receive treatment for Generalized Anxiety Disorder (GAD) despite a high prevalence in this population and significant associated health care costs. Although older adults generally prefer psychotherapy to medication for help with anxiety, face-to-face psychotherapy is difficult to access for many of them. Psychological guided self-help (GSH), which patients use by themselves at home under the supervision of a licensed mental health provider (e.g., psychologist), has been shown to be effective. However, the capacity of our health care system to respond adequately to the mental health needs of seniors has been questioned and cost-effective solutions are required. Because the therapist's role in GSH is limited to supporting the patient, it is conceivable that this role could be assumed by trained and supervised lay providers (LP) instead of licensed providers. If this approach is effective, it could help provide many older adults with much needed mental health treatment at a lower cost. The main objective of this project is to evaluate the effectiveness of GSH guided by LP for GAD in older adults. Participants will be assigned randomly to an experimental group, which will receive treatment immediately, or to a control group whose treatment will be delayed. Data will be obtained through clinician evaluations and self-assessment questionnaires. They will include socio-demographic characteristics, symptoms of GAD, variables related to anxiety, such as depression and sleep difficulties, and participants' perception of treatment. For the experimental group, data collection will take place at four different times: before treatment begins, after treatment ends, and at 6 and 12 months after the end of treatment. Control group participants will be assessed on three occasions: before and after the waiting period and after receiving treatment. The efficacy of GSH will be established by comparing the change in the two groups on the main variables. We will also identify the characteristics of patients associated with improvement during treatment and document their perception of treatment.