The experiment reported measured the degree to which cloze tests deliberately biased on the basis of contrastive analysis would actually be harder for Vietnamese than for speakers of other languages. The experiment tested the approach to ESL (English as a second language) for Vietnamese described in a guide for teachers of Vietnamese refugees published by the Center for Applied Linguistics. The approach maintains that the teacher of Vietnamese students can tell in advance which lessons will be difficult for students by comparing the structure taught with the parallel structure in Vietnamese. Three hypotheses were tested: (1) Vietnamese mean scores on three biased tests were expected to be lower than on the control; (2) the mean score of the Vietnamese on a double-biased test was expected to be lower than on both a selected deletion test and the "salted" test (a test loaded with structures predicted to be hard for Vietnamese); and (3) Vietnamese scores on biased tests adjusted for the covariate control test were expected to be lower in every case than similarly adjusted scores for speakers of other languages. Subjects included 37 Vietnamese, 26 other non-natives, and 9 native speakers of English. Results offer no evidence of a difference in performance due to native language interference for the Vietnamese group. (CLK)