Both the current school reform and standards movements call for enhanced quality of instruction for all learners. Recent emphases on heterogeneity, special education inclusion, and reduction in out-of-class services for gifted learners, combined with escalations in cultural diversity in classrooms, make the challenge of serving academically diverse learners in regular classrooms seem an inevitable part of a teacher's role. Nonetheless, indications are that most teachers make few proactive modifications based on learner variance. This review of literature examines a need for "differentiated" or academically responsive instruction. It provides support in theory and research for differentiating instruction based on a model of addressing student readiness, interest, and learning profile for a broad range of learners in mixed-ability classroom settings.