The main goal of this study was to investigate the contribution of transcription skills to written composition in Spanish beginning writers. For this purpose, we tested models by pen and keyboard modes in which handwriting/typing and spelling were specified to correlate with each other against models in which these two skills were specified to load on a higher-order transcription factor. The study sample consisted of 1124 beginning writers of Spanish (i.e., grades 1-2) from 11 schools in the Canary Islands. We used structural equation modeling to test the contribution of transcription and its specific components to these Spanish pupils' written text production. This analysis revealed that in pen mode, handwriting fluency and spelling directly contributed to writing fluency in free composition at the sentence level, with handwriting fluency contributing less than spelling and spelling contributing both to narrative writing and writing fluency. As regards writing by keyboard, typing fluency and spelling, both taken together and separately, contributed to writing fluency.