Schema instruction improves word-problem solving for students with mathematics difficulty (MD; e.g., Powell et al., 2015); however, prior research suggests that students need word-problem-specific language comprehension in addition to schema knowledge to build word-problem models (Fuchs et al., 2015, 2018). Students have general word knowledge (e.g., "more, less") but require word-problem-specific word knowledge to solve word problems successfully (e.g., "more than, less than"; Kintsch & Greeno, 1985). Prior word-problem schema interventions have not provided explicit instruction in word-problem vocabulary to support students' development of word-problem models. We aimed to determine if word-problem vocabulary instruction combined with schema instruction provided an advantage to word-problem solving for third-grade students with MD. We randomly assigned 75 third graders with MD to three conditions: Word-problem intervention with explicit vocabulary instruction (WP + V), word-problem intervention without explicit vocabulary instruction (WP-only), and business-as-usual intervention (BAU). Students in the treatment conditions received 22, 50-min lessons provided virtually in small groups. On a word-problem vocabulary measure, students in the WP + V condition significantly outperformed students in the WP-only (ES = 0.43) and BAU (ES = 0.83) conditions. On a word-problem measure, students in the WP + V condition outperformed students in the WP-only (ES = 0.08) and BAU conditions (ES = 0.43), although these were not statistically significant. These findings provide preliminary support for the benefits of incorporating explicit vocabulary instruction in a word-problem schema intervention; future research is needed to fully understand the effect of vocabulary instruction on word-problem outcomes.