This study examined the influence of first language (L1) orthographic experiences on decoding and semantic information retention of new words in a second language (L2). Hypotheses were that congruity in L1 and L2 orthographic experiences determines L2 decoding efficiency, which, in turn, affects semantic information encoding and retention. College-level English L2 learners with typologically similar (Korean) and dissimilar (Chinese) L1 backgrounds were participants. Their decoding efficiency was measured by a pseudoword naming task with phonologically regular and irregular conditions. They learned the meaning of the pseudowords paired with pictures. Subsequent recall tasks showed that the Korean group had better overall retention but greater impairment with the irregular pseudowords. These findings suggest that L1 orthographic distance influences L2 word learning processes.