<p>We examined kindergarten, first-grade, and third-grade children’s and adults’ (<i>N</i>=70) evaluations of conclusions drawn from patterns of evidence varying in conclusiveness in both scientific and non-scientific contexts. For scientific problems participants rated their certainty about unseen properties of newly discovered animals. For non-scientific problems participants rated their certainty about the unseen content of boxes. For the non-scientific problems all age groups rated inferences based on conclusive evidence as more certain than judgments based on inconclusive or uninformative evidence. For the scientific problems third-grade children and adults rated inferences based on conclusive evidence as more certain than judgments based on inconclusive or uninformative evidence, in their certainty ratings kindergarten and first-grade children did not distinguish inferences based on conclusive evidence from judgments based on inconclusive evidence or guesses based on uninformative evidence. Younger children appeared to have difficulty applying evidence evaluation skills when asked to make novel conclusions for scientific problems.</p>