Schools are increasingly adopting adaptive learning software to better customize instruction to students' personal needs. While personalized software is not designed to replace the teacher, it does change teachers' roles and responsibilities. However, research is lacking that examines how teachers implement the software and use the provided data and resources to adapt their instruction to students' needs. In this case study, 11 teachers of English Language Learners (ELLs) participated in a 45-minute interview to better understand their perceived responsibilities when implementing adaptive learning software and their obstacles to success. The analysis found that teachers worked to support students by (a) orienting students to the software and learning expectations, (b) troubleshooting technical issues, (c) motivating students to fully engage with the software, (d) monitoring students' behavior and learning in the system, and (e) providing students with additional instruction in small groups or individually. While teachers recognized the need to provide students with individualized instruction using the assessment data and resources provided by the software, teachers largely did not feel prepared or able to provide students with the level of instructional support that they believed was needed. Specifically, teachers highlighted the following obstacles that prevented them from fulfilling their perceived instructional responsibilities: (a) lack of time, (b) lack of preparation and professional development, and (c) the inability to easily obtain and interpret learning data and resources. The article concludes with recommendations for both researchers and practitioners.