Mr. Yapa was the secretary of the Sri Lanka Association of Occupational Therapists (SLAOT) from 1983 to1988. He was also the Sri Lanka Society of occupational therapists (SLSOT)'s founder secretary for unbroken 20 years from 1988 to 2018. He represented the Sri Lanka Society of Occupational Therapists at the World Federation of Occupational Therapists Congress and council meetings as the first alternate delegate.
WFOT acknowledges Paduma’s contribution to the Federation and the profession.