The document discusses several influential theorists of child development across seven theoretical approaches: biological, behaviorism, psychodynamic, cognitive-developmental, cognitive process, sociocultural, and developmental systems theories. It provides brief biographies of key theorists such as Jean Piaget, Lev Vygotsky, B.F. Skinner, Sigmund Freud, John Bowlby, and Mary Ainsworth, outlining their major contributions to understanding child development from different perspectives. The theories focus on both nature-based and nurture-based explanations for child development.