To help students with learning difficulties and disabilities improve their achievement in mathematics, teachers need a full understanding of why these students struggle. This is the first definitive research volume that explores the evidence base for students' difficulties with mathematics. More than 35 internationally known contributors from diverse fields share their expertise on risk factors for poor mathematics outcomes, connections between mathematics and reading disabilities, neuropsychological factors, information-processing deficits, math anxiety, and more. Comprehensive and multidisciplinary, this book gives educators the foundation they need to advance research, teaching strategies, and policies that identify struggling students--and help them improve.