Coleman studied anthropology and zoology at Southern Illinois University Carbondale, and psychiatric social work at the Simmons College School of Social Work in Boston. He did further studies in anthropology at Brandeis University and sociology at the University of New Hampshire. Coleman taught at New England universities from 1980 to 2004, also having been a senior researcher at the Edmund S. Muskie School of Public Policy from 1983 to 1996, before retiring from teaching to write, lecture, and consult.

Coleman writes on popular culture, animal mysteries, folklore, and cryptozoology. An editor of the Skeptical Inquirer said that "[a]mong monster hunters, Loren's one of the more reputable, but I'm not convinced that what cryptozoologists seek is actually out there." He has appeared on television and radio interviews about cryptids. He has written articles and books on cryptozoology and other Fortean topics. He was a publicity consultant on The Mothman Prophecies.

Coleman has carried out fieldwork throughout the United States, Canada, and Mexico, regarding sightings, trace evidence, and Native peoples' traditions of Sasquatch/Windigo/Bigfoot. He has written on Yeti and Bigfoot expedition sponsor Tom Slick and appeared on NPR discussing the death of Grover Krantz. Coleman has won awards for this documentary and literary work.

Paraview Press introduced a series of books, "Loren Coleman Presents" in 2004. Coleman wrote introductions to volumes in the series.

International Cryptozoology Museum

Coleman established his International Cryptozoology Museum in 2003 in Portland, Maine.

Coleman contributed to the exhibition "Cryptozoology: Out of Time Place Scale," shown at Bates College Museum of Art (June 24 - October 8, 2006) and at the H & R Block Artspace at the Kansas City Art Institute (October 28 - December 20, 2006). He delivered the keynote address, "An Introduction to Cryptozoology," at the symposium at Bates College in October 2005, and gave a similar talk at the American Museum of Natural History in 2007.

Coleman is also a contributor/coauthor to the 2006 Bates exhibition catalogue and book, Cryptozoology: Out of Time Place Scale (JRP/Ringier Books, Switzerland, 2006). He also wrote the essay “Cryptids” for Alexis Rockman (Monacelli Press, 2005).

The new location for the museum opened in November 2009. It occupies the rear of The Green Hand, a Portland shop specialising in weird fiction.

The museum was named Yankee magazine's "Best Quirky Museum" in their Maine Best Attractions 2010 list.

Coleman has a masters in social work and acts as a consultant for the Maine Youth Suicide Program. A specific concern is murder-suicides among the young, as well as the possibility of clusters and the influence of media coverage, leading to his writing of The Copycat Effect. He has been called on for statements in the aftermath of school shootings and how best to respond to the problem.