Born of Mexican parents, Ofelia Dumas Lachtman is a native of Los Angeles, California, where she still lives.  She attended Los Angeles City schools, including Los Angeles City College and a brief stint at UCLA, before marrying and moving to Riverside, California.  She has a son and a daughter.

During World War II, Lachtman worked as a medical stenographer.  Later, when her two children were grown, she became a group worker and eventually the executive director of the West Los Angeles-Beverly Hills YWCA. She is also a member of PEN International.

When she was twelve, her work appeared in an anthology of children's poetry.  She is the author of numerous bilingual children's picture books, including Big Enough / Bastante grande (Piñata Books, 1998), and the Pepita series: Pepita on Pepper Street / Pepita en la calle Pepper (Piñata Books, 2008); Pepita Packs Up / Pepita empaca (Piñata Books, 2005); Pepita Finds Out / Lo que Pepita descubre (Piñata Books, 2002); Pepita Takes Time / Pepita, siempre tarde (Piñata Books, 2000); Pepita Thinks Pink / Pepita y el color rosado (Piñata Books, 1998); and Pepita Talks Twice / Pepita habla dos veces (Piñata Books, 1995), which was a recipient of a 1996 Skipping Stones Award. 

Her novels for young adults include The Truth about Las Mariposas (Piñata Books, 2007), Looking for La Unica (Piñata Books, 2004), A Good Place for Maggie (Piñata Books, 2002), The Summer of El Pintor (Piñata Books, 2001), Call Me Consuelo (Piñata Books, 1997), The Girl from Playa Blanca (Piñata Books, 1995) and Campfire Dreams (Harlequin, 1987), for which she won the Benjamin Franklin Award for best young adult novel. 

Her work has been translated into French and German.