This study investigated the effect of a four-week socioscientific issues (SSI)-based intervention on sixth-grade students’ argumentative writing and transferability of argument skills across topics. Students in three treatment classrooms engaged in an SSI unit on space exploration while students in three comparable classrooms continued regular space science lessons. Argumentation skills were assessed by individual decision letters about space exploration. Argument transfer was assessed by an essay to address a novel SSI. Treatment students wrote more elaborated decision letters with stronger arguments, relied less on personal ideas, and transferred argument skills to a novel SSI after the intervention. The implications of using SSI as a promising approach to integrating science and literacy learning for diverse adolescents were discussed.