This paper examines three ways in which the Spanish imperfect and preterite are theoretically conceptualized and how such conceptions are realized practically in elementary Spanish textbooks. An attempt is made to present the three approaches as constituting a theoretical progression rather than viewing them as isolated treatments of the same phenomenon. First, the traditional grammatical ideas about the preterite and imperfect from Ramsey (1894) are introduced and correlated with the presentation given in a new college text. Next, the innovations found in Stockwell et al. (1965) are examined along with their application in the elementary Spanish text of which Stockwell was the advising linguist. The traditional ideas are then compared and contrasted with the newer structuralist approach. Finally, the system devised by William Bull (1960, 1965) is examined as it is put into practice in a college oriented textbook. Bull's ideas are discussed in relation to those of Stockwell et al. in order to demonstrate the hypotheses advanced in this paper, i.e., that there is a growing trend toward a comprehensive explanation of the Spanish past tense. (Author)