In light of the new Swedish Social Services Act, which aims to transform social work in a more preventive, accessible, and evidence-based direction, there is a growing need for proven knowledge and scientific studies on preventive social work that address the social challenges of contemporary Swedish society. This article aims to provide insights into the understanding, planning and establishment of preventive social work practices in response to the new legislation, within a local context. The empirical material includes 1. interviews with social workers and first-line managers employed within a newly established unit for preventive services, 2. a survey distributed to social workers operating in a joint intake, 3. workshops with the management group of the social services organization, and 4. strategic documents. The results indicate that preventive social work is understood as interventions aimed at preventing or counteracting the emergence of social problems. It is operationalized into group- and community-level interventions targeting children and parents to strengthen protective factors early. To meet this definition the studied municipality establishes an organization with three functions: (1) prevention, (2) assessment, and (3) service provision. The preventive work is conducted in the preventive function by two new units: a generalist joint intake designed to ensure a holistic perspective and accessibility, and a team of preventive social workers implementing evidence-based parent- and child-group programs in collaboration with maternal/child health, youth clinics and towards migrant parents. The preventive social workers show positive outcomes and staff value working in a dedicated preventive role. At the same time, joint intake generalists report difficulties achieving holistic support. New organizational gaps emerge, especially when individual-level preventive interventions are needed, which are not included in the reform and therefore requiring assessment before support can be provided.