Many morphologically ergative languages display asymmetries in the extraction of core arguments: while absolutive arguments (transitive objects and intransitive subjects) extract freely, ergative arguments (transitive subjects) cannot. This falls under the label "syntactic ergativity" (see, e.g. Dixon 1972Dixon , 1994Manning 1996; Polinsky to appear(b)). These extraction asymmetries are found in many languages of the Mayan family, where in order to extract transitive subjects (for focus, questions, or relativization), a special construction known as the "Agent Focus" (AF) must be used. These AF constructions have been described as syntactically and semantically transitive because they contain two non-oblique DP arguments, but morphologically intransitive because the verb appears with only a single agreement marker and takes an intransitive status suffix (Aissen 1999; Stiebels 2006). In this paper we offer a proposal for (i) why some morphologically ergative languages exhibit extraction asymmetries, while others do not; and (ii) how the AF construction in Q'anjob'al circumvents this problem. We adopt recent accounts which argue that ergative languages vary in the locus of absolutive case assignment (Aldridge 2004(Aldridge , 2008aLegate 2002Legate , 2008, and propose that this variation is present within the Mayan family. Based primarily on comparative data from Q'anjob'al and Chol, we argue that the inability to extract ergative arguments does not reflect a problem with properties of the ergative subject itself, but rather reflects locality properties of absolutive case assignment in the clause. We show how the AF morpheme -on circumvents this problem in Q'anjob'al by assigning case to internal arguments.