In typological research on mirativity, discussion often centers on the relationship between mirativity, evidentiality, and epistemic modality (Chafe & Nichols 1987; DeLancey 1997, 2012; Aikhenvald 2004, 2012; Peterson 2010). However, in individual languages, speakers mobilize pragmatic extensions that may differentially blend the categorical distinctions. Athabaskan languages have played a particularly important role in this discussion (DeLancey 2001 cited in Peterson 2010) due to the presence of particles that are said to clearly encode mirativity independent of evidentiality, evidence that mirativity warrants a distinct grammatical category. This paper analyzes the function and distribution of the Navajo enclitic la as it is used by speakers in interaction, based on the Navajo Conversational Corpus (Mithun ed 2015 NSF-DEL project 0853598). In its most frequent use, la functions as an interrogative enclitic to mark information questions (Reichard 1951; Young & Morgan 1987; Willie 1996), however this same form may encode what has been described as mirativity. Like other miratives, la may mark surprise, counter-expectation, discovery, and even reported speech (DeLancey 1990, 1997, 2001; Aikhenvald 2004, 2012). Though the two are seemingly unrelated synchronically, a close examination of the pragmatic functions of these enclitics, as well as consideration of comparative Athabaskan evidence, shows that the two enclitics both provide metadiscourse commentary through contrastive focus on the unexpectedness of a proposition. These data contribute to the goal of better understanding how speakers mark new and surprising information in conversation (Aikhenvald 2004), and also support the interactional relevance of the semantic domain of expectation, subsuming both contrastive focus and surprise (Behrens 2012).