This study attempts to explain the Sri Lankan fertility transition in terms of the pre-transition fertility regime and conditions leading to its destabilization. This study therefore deviates from previous studies of fertility in Sri Lanka which have largely focused upon the post-transitional fertility differentials. From the first formulation of demographic transition theory, education has been used as a significant factor relating to the fertility transition, but Caldwell’s ‘mass educationfertility transition’ thesis can be regarded as the major attempt to explain the relationship between education and the onset of the fertility transition, with education a central explanatory factor in fertility transition theory. My analysis uses existing fertility theory to explain the educationfertility transition relationship, systematically tests that theory and suggests some modification to the theory on the basis of the Sri Lankan experience. The availability of relevant information in Sri Lanka has provided the opportunity to analyse the generations which contributed to the onset of the fertility transition and the continuance of that transition