The study's aim is to test a tailored telemetric intervention to reduce rejection incidence by improving medication adherence in a group of adolescent liver transplant recipients identified as nonadherent by a marker (the Medication Level Variability Index, MLVI).

This is a prospective, multi-center, randomized controlled trial. The study will be conducted in transplant centers in the United States and Canada. Estimated final sample size of 140 after attrition. Pediatric adolescent and young adult (age at enrollment ≥12 and < 20) transplant recipients will be eligible for participation in the study. Eligible participants will be randomly assigned to intervention or control group. An interim analysis to evaluate efficacy will be performed. Missing data will not be imputed for secondary analyses.

Inclusion Criteria:

• The patient is ≥ 12 and < 20 years of age at enrollment.
• ≥2.5 years after last liver transplantation.
• Guardian's consent, adolescent assent at enrollment.
• The patient is prescribed tacrolimus.
• The patient's MLVI (SD of tacrolimus) was > 2 when calculated by the site for a period of 2 years prior to the review date

Exclusion Criteria:

• The patient has had transplant of an organ other than liver.
• The patient is currently listed for any organ transplantation.
• The patient is expected to transition to another service (e.g., adult clinic, another
• hospital) during the two years of the study.
• Pregnant patients.
• A temporary exclusion: the patient is not medically stable or was hospitalized for >48 consecutive hours in the past three months.
• Site PI, study PI, or Medical Monitor determines that the patient should not be a candidate for the intervention due to factors that are not covered in the above criteria.

Study pathologists will perform masked reading of for-cause biopsy slides.