Every day in classrooms across the country teachers are using district, state, and federal standards and assessments to prove their effectiveness, monitor students' progress, and understand students' strengths and needs. Jobs depend on student achievement, and in today's age of accountability, assessment scores define what students have learned (Kincheloe, 2008; Nichols & Berliner, 2008). Use of assessment data has become a part of school culture in the United States and, when used properly, assessments can provide valuable information (Stiggins & Chappuis, 2005). Yet, even though students in the middle grades are assessed early and often, many do not understand why they are being measured or what useful information assessments provide. They think data are only important when they take a test, get a report card, or when standardized test scores are released. Students, who tend to not be assessment savvy, may not see learning as a process or understand where they are in that process, and many may fail to set learning goals for themselves (Dweck, 2007; Dweck & Leggett, 1988; Popham, 2008; Stipek, 2002). However, students can be taught about assessments and take control of their own learning. In response to this, two administrators and a group of middle grades teachers developed student data portfolios (SDPs). This manuscript explains SDPs, the rationale behind them, how they were conceived, how they are being used, and evidence of their effectiveness from the perspective of the students. (Contains 3 figures.)