Tufted titmice nest in a hole in a tree, either a natural cavity, a human-made nest box, or sometimes an old woodpecker nest. They line the nest with soft materials, sometimes plucking hair from a live animal such as a dog. If they find snake skin sheddings, they may incorporate pieces into their nest. Eggs measure under 1 inch (2.5 centimetres) long and are white or cream-colored with brownish or purplish spots.
During the fall migration and winter, chickadees often flock together. Many other species of birds, including titmice, nuthatches, and warblers can often be found foraging in these flocks. Mixed flocks stay together because the chickadees call out whenever they find a good source of food. This calling out forms cohesion for the group, allowing the other birds to find food more efficiently.