This study investigated cross-linguistic influence in acquisition of a second lexicon, evaluating Samoan-English sequentially bilingual children (initial mean age 4 ; 9) during their first 18 months of school. Receptive and Expressive Vocabulary tasks evaluated acquisition of four word types: cognates, matched nouns, phrasal nouns and holonyms. Each word type had varying phonological and conceptual difference between Samoan (L1) and English (L2). Results highlighted conceptual distance between L1 and L2 as a key factor in L2 lexical acquisition. The children acquired L2 lexical items earlier if their conceptual representation was similar to that of L1. Words with greater conceptual distance between L1 and L2 emerged more slowly. This suggests that L1 knowledge influences L2 lexical consolidation for sequential bilinguals. Words that require a conceptual shift from L1 take longer to consolidate and strengthen within the L2 lexicon.