This paper analyzes cross-correlations among six variables of Brazilian Portuguese (the pronunciation of nasal /e/, coda r-retroflexion, coda r-deletion, NP agreement, 3rd person plural subject-verb agreement, and 1st person plural subject-verb agreement), with the objective of identifying constraints that promote the co-occurrence of sociolinguistic variants in individual speakers’ speech. We focus on the perspective of structural cohesion, and show that co-variability is conditioned not only by structural similarities among dependent variables (such as agreement processes or coda weakening), but also by general linguistic constraints that operate across multiple variables, such as phonic salience (Naro 1981, Scherre 1988, Naro et al. 1999). Finally, we suggest that markedness may be a more general linguistic principle underlying co-variation.