It is argued that a grammaticization perspective affords insights on the problem of functional equivalence in variables “above and beyond phonology.” This is a study of variation between aspectual expressions involving Spanish estar ‘be located’ and andar ‘go around’ + gerund. An analysis of Mexican oral corpora shows both linguistic and social conditioning: Each auxiliary is favored by certain classes of main verbs, and andar is favored in popular varieties. Semantic bleaching along parallel paths results in layering in the domain of progressive aspect, while retention results in synchronic distribution patterns congruent with the original meaning of the source constructions. Thus, once meaningful aspectual differences become distributional routines. At the same time, the patterning of verbs denoting outdoor activities with andar leads to social differences and the association of this variant with rural and popular varieties.