In many languages of the world, the focus of a sentence—roughly, information that is new and not presupposed—must be displaced from its thematic position to another position within the clause. In many respects, this displacement resembles the movement of wh-words, also common in many of the world's languages. This dissertation investigates these phenomena, focusing especially on their behavior in San Martín Peras Mixtec. With novel data gathered through linguistic fieldwork, the dissertation addresses a series of questions that have been debated for many years within the linguistics literature: What motivates the displacement of foci? What is the formal relationship between the displacement of foci and the displacement of wh-words? What restrictions ought to be placed on the set of formal features that trigger movement?

In this dissertation, I advance the hypothesis that all syntactic movement of foci and wh-words happens indirectly. Specifically, I propose that a set of Alternative Particles—particles that take scope over elements that generate semantic alternatives—can be attracted in the syntax, moving foci and wh-words with them. Consequently, many syntactic similarities between wh-words and foci can be explained by the fact that they both must appear in the scope of Alternative Particles.

However, I also present evidence from San Martín Peras Mixtec that demonstrates two clear ways that the movements of wh-words and foci are not formally identical: (i) wh-words, but not foci, move within fronted constituents; (ii) wh-words must move across more local foci when they co-occur within the same clause. I propose that these differences are explained, respectively, in the following ways: (i) wh-words, as a lexical class, can bear a formal syntactic feature that triggers their movement independent of Q Particles. Foci, which do not form a lexical class, do not bear a formal feature; (ii) Q particles bear a superset of the features borne by other Alternative Particles. In addition, I advance a theory of syntactic probing that leverages this distinct featural representation of Q Particles to account for the non-local movement of wh-words.