Comprehensive schoolwide initiatives like integrated multitiered systems of support (I-MTSS) and universal design for learning (UDL) present opportunities for large-scale impact on improving teacher instructional practices and, therefore, student outcomes. Specifically, implementing I-MTSS and UDL concurrently presents an opportunity to enhance and improve universal instruction for all students. This mixed-methods study explored current Tier 1 practices in elementary schools across the United States. Findings revealed that I-MTSS and UDL are perceived as being implemented concurrently. In addition, school personnel identified specific barriers to implementation.