Context In Quebec, adult mental health (AMH) first-line teams are mandated to provide psychosocial services to people living with mental health difficulties, including anxiety and mood disorders. Following the establishment of new clinical guidelines in 2017, the duration of interventions was not to exceed 15 sessions, with some exceptions. Objectives The overall aim of the longitudinal component of the Shared Knowledge study was to evaluate the care experience of individuals with an anxiety or depressive disorder receiving a short-term intervention (<15 sessions) by first-line AMH teams, and the evolution of recovery over time. Specifically, the objectives were to: 1) determine the appreciation of short-term interventions by service users; and 2) assess the evolution over time of the symptomatology, functioning and quality of life and recovery of individuals receiving short-term interventions. Method A mixed method longitudinal design was used. Telephone interviews were conducted with participants, in which the following variables were quantitatively and qualitatively assessed: appreciation of services received, quality of relationship with the provider (INSPIRE), depressive symptoms (PHQ-9), anxiety symptoms (GAD-7), global functioning (WHODAS), quality of life (ReQOL), and personal recovery (ERTAD). Linear mixed model analyses were performed to examine changes over time on quantitative measures. Content analysis was performed on the qualitative data. Results A total of 63 individuals participated in an interview before the start of their intervention and 22 of them participated after the end of this intervention. Statistical analyses showed a significant improvement in anxiety symptoms, quality of life, and personal recovery, but no difference was observed in depressive symptoms and level of functioning. Nearly half (47.4%) of participants reported that the intervention they received had "completely" met the need that had led them to seek help, and 33.3% felt "completely" equipped or empowered in their recovery. The quality of the relationship with the caregiver, the opportunity to take part in decision-making, and the personalization of the intervention according to their needs and preferences were some of the elements that were particularly appreciated. Conclusion Short-term interventions seem to be appreciated and produce positive effects in many people suffering from anxiety or depressive disorders. However, they remain insufficient for a number of them. A personal recovery measure should be used in conjunction with symptomatology and functioning scales to monitor the progress of people using first-line mental health services.