The present study looks at the levels of activation of different languages a trilingual language user operates in at the moment of text construction in one of these languages. Forty-eight Portuguese advanced users of English (L2) and intermediate in German (L3) were asked to perform a translation task. The subjects were divided into two subgroups: Group 1 was exposed to the input text in L1 (Portuguese) to be translated into L3, while Group 2 were to translate the same from their L2 into L3. The data collected through simultaneous introspection was compared in terms of languages activated on the level of conceptualisation: macroplanning (content) and microplanning (form), i.e. verbalised thoughts (object-regulation), formulation (encoding: selection of syntactic, lexical and morphological information--object and other regulation) and articulation (the final output--self-regulation). The levels of activation of L1, L2 and L3 were observed as well as intentional versus unintentional switches between languages. It was assumed that the language of input would determine the choice of languages activated in the process of translation. Also language proficiency, learning profiles and mode of language instruction were believed to influence text construction and strategies used. (Contains 7 tables.)