Challenging behavior in the early years of development is defined as “any repeated pattern of behavior or perception of behavior that interferes with or is at risk of interfering with optimal learning or engagement in prosocial interactions with peers and adults” (Smith & Fox, 2003, p. 5). Challenging behavior exists on a continuum of less to more severe, with behavior at the severe end being disruptive and even dangerous. At the less severe end of the continuum, adults may even differ on whether a particular behavior is seen as challenging. All children engage in challenging behavior at some point, but some children engage in challenging behavior that is persistent. It is also important to remember that many infants and toddlers engage in behavior that is challenging (e.g., being difficult to soothe) but nonetheless is developmentally typical.