The present study examines the complex interactions between the spoken and the written language in twenty Funish children’s oral and written narratives and a read out task. Both quantitative and qualitative analyses were conducted. First, a comparison of the distribution of the reduction phenomena in the children’s language across the two spoken conditions was made. The second analysis looked at the distribution of spelling errors in the written narratives with respect to sound and reduction related errors both at a general and individual level. Finally, a qualitative analysis of three children’s distribution of the large weak class was performed to evaluate a possible interaction between the children’s three registers: spontaneous speech, reading and writing. The results indicated that (a) there was a significant difference in the distribution of forms across the two spoken modalities, e.g. schwa-assimilations and schwa-drop and Funish forms occurred less in the read out condition than in the spoken narratives; (b) spelling errors were predominately sound related and could be explained as either related to the opaque phoneme to grapheme relation in Danish or to reduction phenomena in the children’s own language; (c) furthermore, there was a significant correlation between spelling errors and a high frequency of reduced forms in the read out condition indicating a close relation between these two modalities.