The objective of the study is to compare the relative effectiveness of Inductive Thinking Model (ITM) and Advance Organizer Model (AOM) in teaching chemistry under two different boards/councils in relation to level of cognitive achievement of the students on the criteria of immediate learning and retention. The sample consists of 200 students from eight sections of four randomly selected schools situated at Purulia, Birbhum, Malda and Hoogly. The (2 × 2 × 3) factorial design was used for the study. At the beginning, an entry level test (ELT) has been administered to cheek the homogeneity of the groups and to categorize the students on the basis of their cognitive achievement. After administering the entry level test, four treatment groups have been formed. Gr I and Gr III have taught with AOM whereas Gr II and Gr IV taught with ITM for eight weeks. After experimentation, common standardized CRTs (post test)viz. CRT II and CRT III has been administered to all the sections. In order to test retention of the learnt knowledge, CRT IV, which is the combination of CRT II and CRT III has been administered after 15 days from the date of post test. Results indicate that that both ITM and AOM are equally effective on the criteria of immediate learning but AOM group establishes superiority than the ITM group on retention.