This course will focus on current knowledge of various low incidence disorders (those typically represented in one percent of the population or less), especially conditions that are first diagnosed in infancy or childhood. We will discuss both biological and psychological factors playing a role in the etiology and discuss characteristic profiles for specific disorders. We will also consider potential interventions for prevention and treatment of the various disorders. Disorders to be considered include (but are not limited to) mental retardation, autistic disorder, Rett's disorder, Asperger's disorder, tic disorders, selective mutism, pica, enuresis, stereotypy and feeding disorders. For covering course material, the problem-based learning model will be used.