This study evaluated a bilingual intervention in the key learning area of mathematics. Nine typically developing Samoan–English students received math lessons in both Samoan and English. A control group of Samoan–English students received all lessons in English. The material covered and the amount of instruction was the same for each group. The only difference was in the language of instruction. Two assessments measured progress in early mathematical skills and concept development. Initial data from each test in isolation indicated no additional benefit for students who received bilingual intervention. Further analysis revealed two interesting patterns of learning between tests. First, all students more easily acquired rote mathematical skills and knowledge than conceptual knowledge and its associated vocabulary. Second, there were differences in patterns of learning between groups. The control group acquired mathematical skills but made limited progress acquiring conceptual knowledge. In contrast, the intervention group demonstrated more balanced learning: acquisition of core math skills was matched by gains in conceptual development. We propose that bilingual intervention facilitated English word learning, producing improved learning of core skills linked to underlying conceptual knowledge.