Years of cognitive research has shown background knowledge in key subject areas, like science and social studies, is essential to reading comprehension, helping students not only understand the meaning of a text, but also interpret new words and ideas. Failing to provide the opportunity to learn to read has devastating effects on children and alarmingly, the current reality fails some students disproportionately--the number of students reading proficiently drops precipitously for Black students, Hispanic students, English language learners, and students with disabilities. Critical to righting this inequity are well-prepared teachers who can deliver engaging opportunities for students to learn core content foundational for reading comprehension. However, for teachers to provide students with background knowledge to support them in becoming successful readers, they must first gain the knowledge themselves. Teacher preparation programs, therefore, play a critical role in providing aspiring teachers with the content knowledge they need to teach their future students. Are preparation programs achieving this goal? To find out, the National Council on Teacher Quality (NCTQ) engaged experts from the field, teacher preparation program faculty, and measurement experts to design the Building Content Knowledge standard, one of the seven standards of the Teacher Prep Review, to ascertain the extent to which undergraduate elementary teacher preparation programs (and the institutions in which they are housed) build candidates' content knowledge in two core subject areas: science and social studies. [For a list of sponsors of "Teacher Prep Review," see page 28 of the full text.]