The authors argue that insufficient attention has been given to foundational concepts in special education. Two classes of foundational concepts are discussed: human constructions and logico-mathematical facts. Four human constructions are examined: (1) making teaching most important, (2) discriminating among ideas, (3) choosing conceptual models, and (4) responding to diversity. Three logico-mathematical realities are detailed: (1) statistical phenomena, (2) sorting, and (3) labeling. The authors conclude with comments on the importance of better thinking and clearer communication, suggesting that the consequences of poor thinking and communicating are negative for both special educators and their students. Five recommendations for action are proposed.