Despite a large increase in enrollments of students in online courses at the K-12 level, there is very little research on the use of differentiation in fully online (called "virtual") schools. This study asked virtual teachers from two different types of schools to discuss their differentiation practices, and compared differentiation practices of teachers across these schools. Nineteen focus groups consisting of 92 teachers were conducted. Data were analyzed using Tomlinson's differentiation framework. Results showed that the large majority of teacher comments about differentiation definitions, assessments, curriculum, grouping and strategies fell in the novice category, and that newer virtual school teachers may struggle in developing skills in differentiation in an online environment.