She is interested in theorizing and studying issues of race, gender, class, space, and the domestic built environment and processes of community-building. She is actively rethinking the theory and practice of historic preservation to center on the tangible and intangible heritage of marginalized subgroups in the United States and on community-engaged scholarship. She collaborates with the Lakeland Community Heritage Project to document and interpret the history of Lakeland, a nationally significant African American suburb located near the University of Maryland campus. Professor Sies promotes advocacy and social justice in her scholarship and her teaching.