Mary Ann is a Professor of Language and Literacy in the Graduate School of Education at Lesley University in Cambridge, Massachusetts. Prior to that, she served as a curriculum facilitator for English Language Arts and Social Studies at the middle level, and taught English Language Arts, Humanities, and creative writing at the middle and high school level in New York and New Hampshire. At Lesley, she teaches courses in children's and young adult literature and literacy methods, including a specialized course in nonfiction for children and young adults, mentors the content literacy and children’s literature courses, and advises doctoral students. Previously, she served as Program Director of the Collaborative Internship Program, a residency-based teacher preparation program in its fifth decade.

Along with Erika, she is the co-author of Text Sets in Action: Pathways Through Content Area Literacy (Stenhouse, 2021), as well as Teaching with Text Sets (Shell, 2013) and Teaching to Complexity: A Framework for Evaluating Literary and Content-Area Texts (Shell, 2015). She has been a guest on public radio and a consultant to public television, and her work has appeared in English Journal, Language Arts, The Dragon Lode, School Library Journal, and School Library Connection. Mary Ann blogs about children's and young adult literature currently at "The Classroom Bookshelf," a School Library Journal blog and is a founding member and contributor to The Biography Clearinghouse, a project of The Children's Literature Assembly of NCTE. Previously, she reviewed children's and middle grade books for NCTE's Language Arts and served on NCTE's Orbis Pictus Award for Outstanding Nonfiction (K-8) Committee for four years, the final two as committee chair.

Mary Ann is a board member of The Afribuk Society and an Advisory Board Member of CLiF, the Children's Literacy Foundation. She is also writing a young adult biography and has several other writing projects for young people underway.