Crohn's disease and ulcerative colitis affect about 1.6 to 3 million people in the United States with many of those being young children and adolescents. Physicians need better ways to inform decisions on therapy selection and recognize ongoing intestinal injury while on treatment.||The main reason for this research study is to see if a blood test or stool test, which measures specific proteins, taken just before starting a new treatment for Crohn's disease can predict a patient's ability to achieve complete intestinal healing. The investigators also want to see if the intensity of gut inflammation can be detected by measuring a separate set of proteins in the blood.