There is an emerging research base exploring the relation between mathematics vocabulary and achievement; therefore, we conducted a pilot study of a mathematics vocabulary intervention for first-grade students with mathematics difficulty (MD). At posttest, the vocabulary intervention group scored significantly higher than the active control on mathematics vocabulary; growth, however, was not significant. The vocabulary intervention group had significantly higher gains on the Concepts and Communication subtest of a distal measure. While all students began the intervention below the 13th percentile in mathematics, 31% of participants exceeded the 25th percentile at posttest. The results of this pilot study have implications for practitioners working with students with MD, and also make a contribution to the knowledge base on mathematics vocabulary intervention.