The scale development process is widely accepted and used as a quantitative tool to measure constructs in behavioural research. In the present paper, the objective was to develop core competency scale to measure the Knowledge, Attitude, Skills and other attributes of the extension field functionaries working under Land Resource Inventory based watersheds. A deductive scale development approach is adopted for construction of scale. Elaborative steps were followed to develop competency scale that should be parsimonious. In the present scale experts identified six major core competency domain areas like Planning, Communication, Technical, Program implementation, Professional and Information Technology competencies needed by extension field functionaries for effective execution of watershed activities. After judgment and content validity of the instrument, 38 items were selected for final scale and reliability was checked using Cronbach's alpha. The final scale is used to measure the competency gaps existing among extension field functionaries working in Land Resource Inventory based watersheds.