This chapter will focus on the external factors conditioning phonological variation. I will introduce the traditional factors to analyze social variation (e.g. sex, age, social class) and stylistic variation (careful vs. casual speech), as well as other possible factors not fully explored in Spanish. These other factors are mostly inspired by Allan Bell's model of language style as audience design (1984), and Rickford and McNair-Knox's incorporation of addressee and topic of conversation as two important factors to analyze variation (1994).