Jill de Villiers, Ph.D., is the Sophia and Austin Smith Professor in the Departments of Psychology and Philosophy at Smith College. She has four books about language acquisition and numerous chapters and journal articles on the acquisition of complex syntax and other language phenomena in preschoolers. In addition, she has published widely on the interface between language and Theory of Mind. She has co-published two other assessments besides the QUILS and QUILS:ES: a test for African American and other dialect speaking children in the U.S. (The DELV: Diagnostic Evaluation of Language Variation), now published by Ventris Learning Company, and the DREAM (Diagnostic Receptive and Expressive Assessment of Mandarin) in China. She collaborates with colleagues throughout the world on linguistic research and assessment, and has been heavily involved also in the design of language intervention materials.