This paper investigates the contrast between two kinds of clausal complements in the shell noun construction in Portuguese, namely finite clause complements introduced by the conjunction que ‘that’, as in a ideia de que éramos vigiados ‘the idea that we were being watched’, and inflected infinitive complements, as in a idéia de tomarem chá ‘the idea (for them) to have tea’. The aim is to reveal which factors motivate the choice of either the finite complement or the inflected infinitive construction. Three successively more detailed quantitative corpus analyses were carried out: a collostructional analysis, a distinctive collexeme analysis, and a logistic regression analysis. The results show significant differences in the constructional preferences for most nouns, but also reveal 13 nouns that frequently combine with the two complement clause constructions. With these 13 nouns, it was found that a higher degree of complement clause autonomy, complexity, and verbality favored the use of the finite clause alternative.