["Topics in Cognitive Science, EarlyView. ", "\nAbstract\nIn two studies, we test preschoolers’ ability to compare abstract relationships across sets. In Experiments 1a−1d, we show that both older (4‐ and 5‐year‐olds) and younger (3‐year‐olds) preschoolers successfully match both monotonic and symmetric relationships in visual patterns and succeed both in direct relational matches and inverted ones (e.g., the target was a big circle, a small circle, big circle and the match was a small square, big square, small square). In Experiment 2, we show that 4‐ to 6‐year‐olds can compare more complex abstract relationships among sets, including relative set size, proportions, means, and modes. These results are consistent with the view that some of the culturally acquired epistemic practices used for scientific inquiry emerge, in their simplest forms, in early childhood.\n"]