Steven Paul Lalley (born 16 January 1954) is an American statistician and mathematician. Lalley graduated in 1976 with B.S. from Michigan State University. He received in 1981 his Ph.D. from Stanford University with thesis Repeated Likelihood Ratio Tests for Curved Exponential Families under the supervision of David Siegmund. After teaching at Columbia University and Purdue University, Lalley became in 1998 a professor of statistics at the University of Chicago and served as department chair from 2001 to 2005.