Inflammatory bowel disease (IBD) is a chronic condition that causes inflammation of the intestinal tract. Common types of IBD include Crohn's disease, ulcerative colitis, and indeterminate colitis. Infliximab (Remicade®) is a biologic medication that is approved by the U.S. Food and Drug Administration (FDA) for the treatment of IBD. Previous research with infliximab has shown it to be an effective treatment for pediatric IBD, however, it can become less effective if the level of the medication in the body is not high enough or if a patient develops antibodies (proteins made by the immune system that attack foreign substances in the body) to the medication. Currently, if a patient with IBD is taking infliximab and develops either abnormal lab values or reports a worsening of symptoms the doctors will measure the level of infliximab in the blood as well as any infliximab antibodies to determine if dosing changes, to either the dose of the medication or the frequency of dosing, are needed. This process is called reactive drug monitoring. The purpose of this research study is to find out if proactive drug monitoring in patients being treated with infliximab for IBD works better for controlling IBD. Proactive drug monitoring is measuring the level of infliximab in the blood as well as infliximab antibodies on a regular basis, before symptoms worsen or lab results come back abnormal, to see if dosing changes can be made that may prevent the worsening of IBD.