Abstract: In many languages, habitual statements such as "my father smokes" can be expressed in two major ways (Carlson 2005, 2012). The first employs a relatively unmarked verb, arguably realizing imperfective grammatical aspect. In the second type of habitual sentence, however, the verb bears special ‘habitual’ morphology. In this talk, I will examine this contrast between 'imperfective-marked' and 'habitual-marked' habitual sentences in the Tlingit language (Na-Dene; Alaska, British Columbia, Yukon). Although there is a significant overlap in the use of these two verb forms, certain semantic contrasts do exist. Most notably, the habitual morphology of Tlingit cannot be used to express pure, unrealized ‘dispositions’/‘functions’/‘duties’ (e.g., ‘Mary handles any mail from Antarctica’). In other words, Tlingit habitual morphology – unlike imperfective aspect – requires the ‘habituality’ in question to have actually occurred, an effect that has also observed for specially marked habitual-constructions in a variety of other, unrelated languages (Green 2000, Bittner 2008, Boneh & Doron 2008, Filip 2018). I develop and defend a formal semantic analysis that captures these (and other) contrasts between imperfective and habitual verbs. In brief, imperfective aspect is argued to possess a modal semantics, quantifying over alternative worlds/situations (Menendez-Benito 2013, Arregui et al. 2014). Habitual morphology, however, is argued to be associated with a (potentially covert) temporal quantificational adverb, one that quantifies strictly over times in the actual world. The consequences of this account for the analysis of habitual sentences in other languages are explored.