The typological variation between the Nordic languages offers a “natural laboratory” for the cross-linguistic study of first language acquisition. Based on an on-going inter-Nordic project, the present article discusses research designs for the exploration of this laboratory together with pilot analyses of acquisition data across Danish, Finnish, Icelandic, Norwegian and Swedish. On the basis of evidence from longitudinal case studies, from narrative tasks, and from morphological and phonetic experiments, the project aims at producing an integrated picture of the development of grammatical morphology and its interaction with (a) the semantic domains of spatial and temporal relations and (b) the prosodic domains of tonal word accents and duration. In the present article the focus is on spatial relations and prosody. Comparisons of developmental data between languages that show considerable typological differences (Finnish vs Icelandic vs the Mainland Scandinavian languages) allow us to establish broad cross-linguistic commonalities in acquisition structure. It is shown that, across all five languages, very similar relational concepts are encoded by the first grammatical morphemes emerging in the field of spatial relations. The impact of linguistic details on acquisition structure can be explored with greater precision through comparisons between languages that show minimal typological differences (the internal differences between the Mainland Scandinavian languages: Danish vs Norwegian vs Swedish). Here, the early development of the Verb + particle construction in two Danish and two Swedish children is analysed. Language-specific effects on acquisition structure of syntactical and prosodic traits are demonstrated. Further, language-specific effects on the development of verb argument structure in spatial descriptions are discussed.