The Preschool Temperament Study took place in the Temperament, Emotion, and Relationship Processes (TERP) Laboratory at Williams College. It was a research project examining individual differences in children’s personalities and emotions as well as mother-child interactions. We were interested in examining children’s responses to various situations by measuring their behavior and biological responses. We examined these responses across an entire group of children and were able to develop a greater understanding about preschoolers’ emotional development.