The present study attempts to explore how L1 sociopragmatic knowledge and pragmalinguis-tic selection influence the Japanese and Chinese Efl learners' interlanguage (IL) requests in terms of supportive moves in English. Forty-eight Japanese and fifty-four Chinese English-major university students participated in the experiments. Their use of supportive moves as external downgraders in their L1 and IL requests was analyzed and compared. The data were collected by means of an open Discourse Complete Test (DCT). A two factor ANOVA was employed to examine if Power factor and Language difference factor influenced their IL requests significantly. Results showed that L1 sociopragmatic knowledge and Power factor have a strong influence on the use of supportive moves in IL requests in both Japanese and Chinese Efl groups. However, only Chinese Efl learners displayed a strong influence from L1 pragmalinguistic selections on the use of supportive moves.