O'Neill, Duffy & Co., LLC is a real estate appraisal and consulting firm that works to provide clients expertise in all areas of real estate appraisal. Individual appraisers concentrate their efforts in specific areas of appraisal to maximize their skills and knowledge for the client. At the same time, the firm emphasizes coordination and cooperation between appraisers to best serve all the client needs. Terrence Duffy is the primary appraiser with over 20 years experience. He receives assistance and consulting on an as needed basis from Frank O'Neill, Jr, SRA.

The firm provides real estate valuation services for both Residential Property and Income Property. The Residential Property work includes a wide assortment of residential properties, from small condominium units to large multi-million dollar estates. The Income Property Department offers appraisal services for a broad array of commercial, retail, office, industrial and special purpose property.