Seven postulated stages of acquisition of Spanish as a second language are examined within the context of Processability Theory, whose predictive paradigm is applicable to interlanguage development in any second language (L2). The theory argues that the sequence in which the target language unfolds in the learner is determined by the sequence in which processing prerequisites needed to handle the language's components develop. The logic, concepts, and principles underlying processability are first outlined. Development of grammar, a lexical-functional model, the nature of agreement in Spanish, and word order are then discussed in relation to processability. Finally, the seven stages are examined and charted. It is concluded that, viewed from this perspective, the seven stages of acquisition are distinct. Appended materials include notes on learner language and examples of interlanguage. Contains 17 references. (MSE)