The purpose of this study was to determine effectiveness of constant time delay procedure on learning to recognise functional sight words with two subjects. The participants were two adolescents with severe intellectual disabilities. A multiple baseline design across participants was employed to evaluate its effectiveness. The results of the present study were effective for subject-1 as he achieved criteria but subject 2 could not achieve criteria of learning to recognise. given 5 sight words, (learnt only 4 words) within 25 sessions. Maintenance sessions were conducted after 2nd and 4th week after intervention and subject-1 retained to recognize only three sight words. Subject -2 retained all four sight words that he learns during intervention.