As K-12 online learning continues to grow for all student populations, so should knowledge of best practices related to teaching students with diverse learning needs, including students with disabilities. The absence of a strong literature base provides a unique opportunity to explore teacher knowledge in these settings, particularly as they consider their role in the call for highly skilled, high-quality instruction for all students, regardless of disability status. This study explored descriptions of practice from fully-online teachers in their instruction of students with disabilities. Data were collected using semi-structured interviews of online teachers across a variety of grade levels. Analysis involved both thematic and theoretical elements to identify concepts for interpretation. Findings were divided into two major concepts: (1) online teachers' learned practices about working with students with disabilities; and (2) online teachers' sources of knowledge about "good" teaching practices when working with students with disabilities.