The objective of this trial is to test whether a smartphone app, SMART-IBD, is effective in improving medication adherence and self-management skills in adolescents with IBD. The investigators will conduct a randomized control trial to compare 35 youth (ages 13-17) with IBD using an app that contains daily symptom diaries, education content, medication reminders, as well as monthly engagement challenges to 35 youth in an attention control group that will complete daily diaries. The length of the intervention will include one month of baseline symptom and adherence collection, a baseline assessment, 5 months of intervention, and a post-treatment assessment.

Inclusion Criteria:

• Confirmed diagnosis of IBD (Crohn's Disease, ulcerative colitis, or indeterminate colitis)
• Prescribed at least one daily or weekly medication for treatment of IBD
• <86% adherence to prescribed medication
• Access to internet via Wi-Fi or data plan and access to smartphone
• English fluency for patient and caregiver

Exclusion Criteria:

• Diagnosis of pervasive developmental disorder in patient or caregiver as determined by medical chart review
• Diagnosis of serious mental illness (e.g., schizophrenia) in patient or caregiver as determined by medical chart review

The study PI, statistician, co-investigators, and all personnel who are involved in endpoint analyses will be blinded. Only study coordinators will have access to the assignment of each participant.