Multilingual families face decisions about the linguistic upbringing of their children. These decisions shape their family language policy (FLP) which potentially impacts the children and their family. Departing from this hypothesis we conducted a systematic literature review applying the PRISMA guidelines, screening three databases, using search terms related to FLP (building on Spolsky's framework). After a title- and abstract-based initial screening, 191 retained articles were scanned for a connection between FLP (components) and outcomes. We classify forty-two studies that describe such a link in multilingual families with focal children under the age of thirteen. Based on our results, we argue that studies exploring the socio-emotional (9) and cognitive outcomes (13) are underrepresented, especially because all but one of these studies also largely focus on linguistic outcomes (41). When it comes to the separate components of FLP, practices are found to have the most impact (41 studies), either exclusively (16) or combined with management (12), beliefs (6) or both (7). Based on this review, we recommend future studies to further explore the socio-emotional and cognitive spheres and all their aspects, preferably in families with young children, including families from various language groups or communities, and adopting a longitudinal design.