Born in Dublin in 1956 and brought up in Goatstown, Marita went to school at the Convent of the Sacred Heart, Mount Anville, later working in the family business, the bank, and a travel agency. She has four children with her husband James, and they live in the Stillorgan area of Dublin.

Marita was always fascinated by the Famine period in Irish history and read everything available on the subject. When she heard a radio report of an unmarked children's grave from the Famine period being found under a hawthorn tree, she decided to write her first book, Under the Hawthorn Tree.

Published in May 1990, the book was an immediate success and become a classic. It has been translated into over a dozen languages, including Arabic, Bahasa, French, Dutch, German, Swedish, Italian, Japanese and Irish. The book has been read on RTÉ Radio and is very popular in schools, both with teachers and pupils. It has been made a supplementary curriculum reader in many schools and is also used by schools in Northern Ireland for EMU (Education through Mutual Understanding) projects. It was also filmed by Young Irish Film Makers, in association with RTÉ and Channel 4. This is available as a DVD.

Marita has written more books for children which were also very well received. The Blue Horse reached No. 1 on the Bestseller List and won the BISTO BOOK OF THE YEAR Award. No Goodbye, which tells of the heartbreak of a young family when their mother leaves home, was recommended by Book Trust in their guide for One Parent Families. Safe Harbour is the story of two English children evacuated from London during World War ll to live with their grandfather in Greystones, Co Wicklow and was shortlisted for the BISTO Book of the Year Award. A Girl Called Blue follows the life of an orphan, trying to find who she really is in a cold and strict orphanage. Marita has also explored the world of fantasy with her book In Deep Dark Wood.

Marita has won several awards, including the International Reading Association Award, the Osterreichischer Kinder und Jugendbuchpreis, the Reading Association of Ireland Award and the Bisto Book of the Year Award.