Adults' and kindergarten through fourth-grade children's evaluations and explanations of inductive inferences, deductive inferences, and guesses were assessed. Beginning in kindergarten, participants rated deductions as more certain than weak inductions or guesses. Beginning in third grade, deductions were rated as more certain than strong inductions. Adults and fourth-grade children differentiated strong inductions, weak inductions, and informed guesses from pure guesses. Adults' and fourth-grade children's evaluations of inferences were influenced by the sample of evidence provided and by population base-rate information. By third grade, participants also gave different types of explanations for their deductions and inductions. These results are discussed in relation to children's concepts of cognitive processes, logical reasoning, and epistemological development. (Contains 3 tables and 1 figure.)