Introduction: Theories and Methodologies of Individual Differences in Reading

This opening chapter situates reading as a complex, interactive, and strategic process shaped by linguistic, cognitive, affective, and contextual conditions and argues that understanding reading development requires explicit attention to individual differences (IDs). It first clarifies the nature of reading and contrasts intensive reading and extensive reading as complementary instructional approaches with distinct pedagogical purposes. It then synthesizes emerging scholarship on IDs in reading and frames IDs as essential for explaining why learners with similar instruction often show markedly different reading outcomes. The chapter next introduces the organization of the edited volume: each chapter integrates conceptual foundations, identifies research gaps, provides methodological guidance, and concludes with a concrete template for designing a future study. Finally, the chapter summarizes how the volume advances ID-and-reading research by broadening the construct space (cognitive, linguistic, affective, and sociocultural), foregrounding methodological rigor and innovation (e.g., longitudinal, mixed-methods, modeling, and microanalytic approaches), and offering hands-on scaffolds for graduate students and early-career researchers.