This paper compares the initial state of second language (L2) and third language (L3) acquisition for English articles to examine the influence of L2 proficiency on positive transfer from L2 to L3. We tested 36 L1 Turkish/L2 German adolescent learners of L3 English (L3 group), 41 L1 Turkish adolescent learners of L2 English (L2 group), and 10 native English speakers (L1 group) on a forced-choice elicitation task involving English articles. The overall results from both tasks showed that L3 group was significantly more accurate than L2 group in the four article contexts: [-definite; +specific] and [ + definite; -specific], [ + definite; +specific] and [-definite; -specific], which confirms morhosyntactic positive transfer from L2 German to L3 English. The further analysis of the L3 group revealed that L3 learners with high L2 German proficiency were significantly more successful than those with low L2 German proficiency in the four article contexts. This confirms that L2 proficiency is a determining factor in the positive morhosyntactic transfer from L2 to L3. The results from error analyses revealed that the L2 group committed more substitution errors than omission errors suggesting fluctuation between definiteness and specificity settings of universal semantics rather than negative transfer from L1.