Handoff miscommunications are a leading cause of medical errors. A structured handoff is an effective communication tool. We introduced the I-PASS Handoff Bundle for resident sign-out in the inpatient setting. We aimed to reduce preventable adverse events and unexpected floor calls while also improving residents' confidence and preparedness to care for patients overnight. We conducted an observational study at a single-site family medicine residency between April 2019 and March 2020. Residents received trainings in the I-PASS standardized handoff through didactic lectures and on-the-job sessions in September and November 2019. We evaluated the effectiveness of the I-PASS Handoff Bundle by comparing pre- and postimplementation data including number of medical errors and unexpected floor calls, along with residents' reported levels of preparedness and confidence to care for patients overnight. Prior to the I-PASS intervention, more than half of resident surveys included at least one unexpected floor call whereas postintervention about one-third of resident surveys included unexpected floor calls (P<.05). However, the intervention did not significantly affect residents' confidence level in caring for patients overnight and residents' rating of the usefulness of anticipatory guidance for managing night floor calls. We did not identify any medical errors related to communication issues at patient handoff within the family medicine service. I-PASS intervention significantly reduced unexpected floor calls. However, the intervention did not improve residents' reported confidence and preparedness to care for patients overnight.