Spelling is a language problem-space, not only a school subject. Successful spelling demands going beyond letter to sound mapping and gaining access to a full representation of the orthographic structure of words. We traced bilingual Catalan/Spanish speakers' spelling performance in Catalan across elementary school in two tasks: isolated words to dictation and text-composing. Our first goal was to tap the effect of grade level and task on the quantity and types of spelling errors children produce. Our second goal was to prove whether a more accurate spelling of orthographically ambiguous words (i.e., words with alternative phonographic spellings but only one that is orthographically correct) would explain spelling performance in text-composing. Results show that inaccurate spelling decreased significantly with grade level and was higher in dictation than in text-composing. However, lexical and, especially, orthographic errors were found in children's production until the end of elementary school. Better spellers of orthographically ambiguous words committed fewer errors when producing texts. These findings point at an early implicit awareness of spelling difficulty but a protracted command of ruled orthographic knowledge. [Translation from English by Silvia Montero.]