Lucille Lang Day (born December 5, 1947) is an American poet, writer, and science and health educator. Day has authored or edited 20 books and is a contributor to over 50 anthologies. She is best known as a poet and writer for her award-winning memoir, Married at Fourteen: A True Story, for her integration of science imagery and concepts into poetry and for advocating use of poetry as a tool in environmental activism. As a science and health educator, her many achievements have included promoting science education for girls and serving as codirector of Health and Biomedical Science for a Diverse Community, a project that was funded by the National Institutes of Health and aimed to make biomedical science more accessible to underrepresented minorities.