This teacher‐research study responds to the Common Core State Standards (CCSS) call for an integrated model of literacy that simultaneously builds deep content knowledge and develops students' proficiency in writing arguments in science. The author notes that while argument is a cornerstone of the CCSS writing standards, little attention is paid to the issue of “voice.” Asserting that voice is often what makes arguments compelling, the author urges teachers to engage students in the formal study of “voice” while teaching opinion/argumentative writing. The author describes a “science sleuth” simulation unit she implemented to help students perform the production strategies necessary for composing “voiced” scientific arguments. Using grounded theory methodology, the author presents student writing samples to spotlight the challenges, benefits and potential pitfalls of encouraging sixth graders to write scientific arguments with voice—authority, conviction, commitment, and a command of the subject matter.