This article reexamines Bley-Vroman's original (1990) and evolved fundamental difference hypothesis that argues that differences in path and endstate of first language acquisition and adult foreign language learning result from differences in the acquisition procedure (i.e., language faculty and cognitive strategies, respectively). The evolved…

Theoretical assumptions and consequences of the Markedness Differential Hypothesis (MDH) are compared with the Contrastive Analysis Hypothesis, and empirical evidence favoring the former is reviewed. Pedagogical implications of the MDH, a strategy for interlanguage-intervention, and several problems revealed in the literature are discussed. (MSE)