Landsmann graduated from St. Lawrence University and began her career as a classroom teacher. She taught English in West Africa, and kindergarten in western New York State as part of a pilot program for migrant labor children.
She stepped into educational publishing from the classroom, joining Harcourt Brace Jovanovich (HBJ) from 1970 to 1987. While there she served as editor and publisher of Instructor, the nation's leading magazine for teachers; director of Harcourt Brace Children's Books; vice president of HBJ; and president of Instructor Publications.
In 1988, Landsmann founded her own firm, Leanna Landsmann Inc., to help corporations and associations publish instructional materials for schools. Among others, her clients included TIME and TIME For Kids, Scholastic, AT&T, American Express, American Heart Association, the U.S. Department of Education, Toyota, New American Schools Development Corporation, Marvel Comics, and the White House Historical Association.
Landsmann went on to become the president of TIME Magazine For Kids, where she successfully launched the magazine and led it to become the fastest-growing classroom publication, with a circulation of over 4 million students nationwide. In 1999, she was inducted into the EdPress Hall of Fame. TIME also awarded her the Henry Luce Leadership Award in 2000.
Landsmann has served on Presidential education commissions and visited classrooms in 49 states to observe best practices. She continues to write and speak on education-based topics to the media and to parent-teacher and business groups.