Chapter 3 provides an overview of a number of theoretical proposals that have been put forward in the literature to account for language variation. It elaborates on models that combine formal generative theorizing and quantitative sociolinguistic methodology, in line with current minimalist analyses (Adger & Smith 2005; Sessarego & Gutiérrez-Rexach 2011; Sessarego 2014a). This chapter also stresses the importance of embracing a perspective of mutual complementation – rather than mutual exclusion – between these two fields, especially when the varieties under study consist of stigmatized vernaculars, for which it may be hard to obtain reliable grammaticality judgments and that may be characterized by high levels of inter- and intra-speaker speech variability (Cornips & Poletto 2005).