This paper provides a brief overview of the history of occupational therapy in psychiatry in Ireland and explores why the contribution of an early Irish psychiatrist and proponent of occupational therapy, Dr Eamon O'Sullivan (1897-1966), was not fully recognised in the decades after his retirement in 1962. A review of selected key reports, papers and publications related to the history of occupational therapy was undertaken. Eamon O'Sullivan was appointed Resident Medical Superintendent at Killarney Mental Hospital Co. Kerry in 1933 and developed an occupational therapy department at the hospital from the 1930s until his retirement in 1962. He wrote one of the first textbooks of occupational therapy published in 1955. His occupational therapy philosophy reflects the early decades after the formalisation of the profession in 1917 when beliefs about the curative properties of occupation flourished and professional education programmes were scarce. By the time O'Sullivan's textbook was published it received a lukewarm reception within occupational therapy as it did not reflect 1950s practice and professional philosophy. The professionalisation of occupational therapy in Ireland in the 1960s was also a factor in the lack of acknowledgement of O'Sullivan's contribution to the profession. Practice and professional philosophy change and the paper concludes by considering O'Sullivan's work in light of contemporary occupational therapy which once again places occupation at its centre and emphasises the importance of balance, health and wellbeing.