Background: Perceived high chronic stress is twice as high prevalent among German general practitioners (GP) and non-physician medical staff compared to the general population. The reasons are multi-factorial and include patient, practice, health-care system and societal factors, such as multi-morbidity, the diversity of populations, and innovations in medical care. Also, practice-related factors like stressful patient-staff interactions, poor process management with waiting times, and lack of leadership play a role. This publicly funded study evaluates the effectiveness of the newly developed participatory, interdisciplinary, and multimodal IMPROVEjob intervention on job satisfaction among general practice personnel. The intervention aims at structural stress prevention with regard to working conditions and behavioural stress prevention for leaders and other practice personnel.Methods: In this cluster-randomised controlled trial, a total of 56 general practices will be assigned to either (1) participation in the IMPROVEjob intervention for nine months or (2) the waiting-list control group. The IMPROVEjob intervention consists of the following elements: three workshops, a toolbox with supplemental material, and an implementation period with regular contact to so-called IMPROVEjob facilitators. The first workshop, addressing leadership issues, is designed for physicians with leadership responsibilities only. The two subsequent workshops target all GP and non-physician personnel; they address issues regarding communication (with patients and within the team), self- and team-care as well as practice organisation. During the nine-month implementation period, practices will be contacted by IMPROVEjob facilitators to enhance motivation. Additionally, the practices will have access to the toolbox materials online. At baseline and follow-up, all participants will complete questionnaires. The primary outcome is the change in job satisfaction as measured with the respective scale of the validated German version of the Copenhagen Psychosocial Questionnaire (COPSOQ, version 2018). Secondary outcomes obtained by questionnaires and – qualitatively – by facilitators comprise psychosocial working conditions including leadership aspects, expectations regarding and experiences with the workshops, team and individual efforts, and organisational changes.Discussion: It is hypothesised that participation in the IMPROVEjob intervention will improve job satisfaction and thus constitute a structural and behavioural prevention strategy for the promotion of psychological well-being of personnel in general practices and prospectively in other small- and medium-sized enterprises.Trial registration: German Clinical Trials Register, DRKS00012677. Registered 16 October 2019-Retrospectively, https://www.drks.de/drks_web/navigate.donavigationId=trial.HTML&TRIAL_ID=DRKS00012677.