This article examines the role of tense and mood factors in the selection of complement clauses in Basque, arguing against apparent cases of free variation, discussed here with respect to choice of complement types. In particular, the article concentrates on the ability of some verb classes to take complements in the nominalized form. As with Spanish infinitives, the availability of nominalized complements correlates with the class membership of the main predicate into one of the subjunctive-taking groups. Apparent counterexamples, i.e., predicates which can take both a nominalized/subjunctive complement and an indicative one, will be shown to stem from differences in modality and tense. Variation is considered from a cross-linguistic perspective, and the discussion of the Basque examples is linked to 'double selection' phenomena in Spanish and Romance complements. Particular attention is paid to prospective complements, and a semantic approach is offered to explain why double selection phenomena emerge in this particular case. As expected, while the morphology of Basque and Spanish complement types is strikingly different, the semantic factors intervening in the choice and distribution of complement types will be shown not display the same degree of variation.