The Wisconsin pediatric IBD alliance was formed in January of 2000 to track all new diagnoses of IBD occurring in children younger than age 18. This clinical consortium has successfully recruited 100% of the pediatric GI specialists within Wisconsin to prospectively record all new IBD diagnoses, in order to obtain a population based incidence of CD and UC within the U.S. Between 1/1/00 and 12/31/01, we have identified 192 new cases of IBD within the state. Sixty-five percent of these children were from Southeast Wisconsin, and were diagnosed at Children's Hospital of Wisconsin. In addition to these newly diagnosed children, a cohort of 294 additional pediatric IBD children followed at the Children's Hospital of Wisconsin will serve as a reference population. The focus of this proposal will be to correlate genetic influence on the clinical disease course and behavior using a molecular classification of pediatric CD children in a population based pediatric cohort. This DDC grant will allow the PI and the co-investigator to generate sufficient preliminary data in the under-researched area of pediatric CD and to continue this investigation for support from national foundations (CCFA) and /or the NIH.