Forty-two states and the District of Columbia have adopted the Common Core state standards, while the other remaining eight states are implementing their own new challenging standards for college- and career-readiness. But carefully crafted standards matter little if they do not change how teachers teach. In its latest series of reports, the Center on Standards, Alignment, Instruction, and Learning (C-SAIL) uses new state-representative teacher, principal, and district survey data to understand how college- and career-readiness standards are impacting classroom instruction, what implementation challenges schools face, and which resources educators find most useful in supporting use of the standards.