This paper develops a generative analysis for a particular language contact phenomenon familiar in the variationist and language contact literature, namely indirect transfer [F. Klein, A quantitative study of syntactic and pragmatic indications of change in the Spanish of bilinguals in the U.S, in: W. Labov (Ed.), Locating Language in Time and Space, Academic Press, New York, 1980, p. 69; R. Mougeon, E. Beniak, Linguistic Consequences of Language Contact and Restriction: The Case of French in Ontario, OUP, Oxford, 1991; C. Silva-Corvalán, Language Contact and Change: Spanish in Los Angeles, OUP, Oxford, 1994]. This language contact effect, which is preferential rather than categorical, is difficult to deal with in traditional generative approaches, and has received no attention in this literature. My analysis focuses on Klein’s study of synthetic/analytic verb forms used for the expression of progressive aspect in Spanish, where contact with English causes a skewing in the distribution of use of analytic forms in a bilingual variety compared to a similar monolingual variety. The analysis is carried out in a stochastic OT [P. Boersma, B. Hayes, Empirical tests of the Gradual Learning Algorithm. Linguistic Inquiry 32 (1) (2001) 45–86] framework, where I show that the indirect transfer effects observed by Klein can be captured by way of different ranking of a small set of OT constraints on a linear ranking scale. In addition to providing a model for the indirect transfer effects in Klein’s study, my analysis also makes a typological prediction regarding morphosyntactic expression and Imperfective and Progressive verb forms: no language can have a synthetic Progressive and an analytic Imperfective. This prediction is supported by the absence of any such distribution in the surveys of Bybee et al. [The Evolution of Grammar: Tense, Aspect, and Modality in the Languages of the World, University of Chicago Press, Chicago, 1994] or Dahl [Tense and Aspect Systems, Blackwell, Oxford, 1985].