The interaction between root (i.e. non-epistemic) modal verbs and functional heads like tense and aspect has been investigated in a wealth of recent literature, particularly in the context of counterfactual conditionals (Iatridou, 2000; Arregui, 2009; a.o.) and actuality entailments (Bhatt, 1999; Hacquard, 2006). In this work, I continue this investigation by exploring Spanish modal constructions that express a range of meanings beyond the purely truth-conditional contribution of their constituent parts. First, I focus on a non-cancellable kind of counterfactuality that is triggered by past tense and appears outside the stereotypical conditional environment where such inferences have traditionally been studied. This counterfactual semantic presupposition can arise both in non-conditional declaratives and a specific kind of performative in Spanish. With respect to actuality effects, I argue that the distinction between the French-style languages that trigger actuality entailments and those that do not needn't be a crosslinguistic dichotomy, since the same split can be found "within" a single language. In Spanish, the possibility modal "poder", together with the deontic necessity modal "deber", can be enriched to express either actuality or counterfactuality inferences that appear to be pragmatically derived as conversational implicatures. Conversely, the necessity semi-modal "tener que" (as well as some other necessity modals like "necesitar") trigger standard actuality "entailments". The overall picture that emerges is that a more nuanced reinterpretation of actuality and counterfactuality effects might be necessary because these inferences can have a different range of properties depending on the language where they are found. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]