The purpose of this paper is to present an approach toward evaluating the effectiveness of breast feeding programs in relation to their impact on the duration of post partum amenorrhea. The current emphasis on improving reproductive health through family planning services is likely to increase the use of LAM as a birth spacing method. As a result, evaluation of the net impact of breast feeding duration on the length of post partum amenorrhea is essential for designing an effective family planning program. We present event history analysis as an useful tool in evaluating the effectiveness breast feeding programs on post partum amenorrhea. Data from NFH survey (India) of the State of Rajasthan are used to illustrate the event history approach toward outcome evaluation. (C) 2001 Elsevier Science Inc. All rights reserved.