This paper outlines a procedure for language textbook analysis from the perspective of second language acquisition (SLA) principles as a preliminary procedure to evaluation for selection. The aim is to provide a tool that allows comparison of the potential of textbooks for supporting students' language learning. To this end, ten general principles representing a spectrum of SLA theories were drawn from the literature. Then five EFL textbooks produced in South Korea were analyzed using a minimally modified version of Littlejohn's (Materials development in language tea, 1998, 2011) task analysis schedule. The low-to-medium inference instrument enabled the analysis of all the activities contained in the sampled units, yielding frequency tallies. Final rankings indicated that the procedure did discriminate between the sampled textbooks, revealing a clear cluster of three books that reflected SLA principles more closely. Although only in-use evaluation can determine the extent to which these textbooks actually support language acquisition, the evidence suggests that they are potentially more supportive than the lower scoring books. The procedure outlined in this paper could be of use to language educators, those involved in language materials publishing, and government officials involved in the approval of language materials.