Coleen began teaching EFL at Adam Mickiewicz University in Poznan, Poland in 1975 as a graduate exchange student. In 1977, she moved to Boston, Massachusetts where she worked at the International Institute of Boston as the Co-ordinator for the Special Project for Indochinese Youth and later the Co-ordinator for the Indochinese Adult Refugee Program. From there she moved to San Diego, California where she taught EAP at the American Language Institute at San Diego State University. After moving to England in 1986, she taught EFL in London for a year and then moved to Spain where she gave private lessons while building a house and looking after her baby daughter. She returned to the UK in 1990 and became a teacher-trainer for Trinity College TESOL Certificate at ITS English School before becoming the Head of the School of English at Hastings College of Arts & Technology. Because she wanted to gain experience teaching children, she moved on to become the Director of the International Department at Broomham School, a private boarding school in East Sussex.
Coleen has written two grammar books, as well as numerous readers for other ELT publishers. In the 1990s, she worked as a lexicographer on numerous ELT dictionaries for adults and for children. Taking a short break from EFL in the early 2000s, she worked as a copy-editor and editor of AA travel guides before writing as a main contributor the AA Key Guide to New York. As an author for Macmillan, she has written a Teacher's Guide for one of the Top Deck course books and Assessment Tests for English World's TestBuilder. She now enjoys writing readers for Macmillan Cultural Readers and Children's Readers.