Background: In the German state of Hesse, the language competence of children in German is assessed in (mostly) 6-year-old children during the school enrolment examination. In several regions, it is also assessed in 4-year-olds by means of a large-scale language screening program; however, no representative data on German language skills are available for 5-year-old children. Objective: The current study aimed to quantify German language skills both in monolingual and multilingual 5-year-olds and to analyze sociodemographic variables associated with the need for additional educational or medical assistance in acquiring German. Material and methods: In this prospective cross-sectional study, a total of 908 kindergarten children aged 5;0-5;11 years (52% male, 48% female; 29% monolingual Germans, 71% multilinguals) were tested with the validated language test "Kindersprachscreening" (KiSS.2). KiSS.2 includes subtests on speech comprehension, vocabulary, grammar, articulation, and working memory. Sociodemographic characteristics of children and their families were assessed by KiSS.2-based questionnaires for parents and kindergarten teachers. Descriptive statistics were calculated for children's German language skills according to KiSS.2 and for children's participation in language courses and therapies. By means of classification trees, factors associated with children's need for additional educational or medical assistance in acquiring German were analyzed, with a focus on variables related both to the quality and quantity of the language contact. Results: About one fifth of monolingual German children and more than three quarters of multilinguals were in need of additional educational and/or medical assistance in acquiring German. The difference can be attributed to a much larger proportion of children with educational needs among multilinguals because the percentage of children in need of medical assistance did not differ significantly between these two subgroups. Almost all children who did not speak German at home or who began to acquire it only at the age of 4 years or later did not speak German age-appropriately. Children speaking Turkish and Arabic demonstrated significantly weaker German language skills than other multilinguals. The need for additional educational assistance in acquiring German was most strongly associated with the quantity of the German language input beyond day care centers. Children's medical needs showed the strongest associations (among language contact variables) with not speaking out when playing with other children. Most children with educational needs did not attend German language courses and most children with medical needs did not undergo language therapies. Conclusion: Since more than one half of Hessian preschool children have an immigrant background, it was assumed that most Hessian children do not speak German age-appropriately shortly before school enrolment. This was confirmed for the sample of the current study (57% of fail results in KiSS.2). Some findings indicate that multilinguals are underrepresented both in German language courses and in therapies in comparison with monolinguals. German language skills are clearly associated with the quality and quantity of the language input. For children with minimal language input in German, no sociodemographic variables were identified that would improve their German language competence. This shows that in order to speed up the acquisition of German there is no other way than to optimize the quality and quantity of the language input.