This article focuses on a change affecting Spanish in contact with English in the United States: namely, simplification and loss of Subjunctive (Sub) mood morphology. Conversational data from 17 Mexican-American bilinguals living in the eastern section of Los Angeles are analyzed qualitatively and quantitatively. The speakers represent three different immigrant groups, according to length of family stay in the United States. The variation between Indicative (Ind) and Sub usage attested in the Spanish-speaking world results from the continuing modifications which have affected the distribution of Ind and Sub forms through the diachronic development of Spanish: previously obligatory contexts for the use of Sub are now categorically Ind or allow both Sub and Ind to different degrees across social and geographic parameters. In the Spanish of Los Angeles, the internal tendencies toward a reduction of the obligatory use of the Sub are strengthened, as may be expected in a situation of language contact in which obligatory contexts for the use of a form are more resistant to change than those that allow a selection between two or more forms with closely related meanings.