This study examined the development of flexibility and abstraction in preschool children by using a newly designed Pattern Completion Task (PCT) and the Flexible Item Selection Task (FIST). In the PCT, children were presented with an incomplete pattern consisting of different-colored shapes and were asked to select the colored shape that appropriately completed the pattern. In the FIST, children were presented with three cards, each depicting items that could vary in terms of shape, size, color, and number. Children were asked to first select two cards that matched on one dimension and then to select two cards that matched on a different dimension. Both tasks were administered to 97 three- to five-year-old preschool children. Results from both the PCT and the FIST showed that the ability to flexibly shift between features of objects undergoes major development during the preschool years. Furthermore, difficult items from both tasks were significantly correlated, indicating that the same flexibility component underlies performance in both tasks. (Contains 2 figures and 3 tables.)