The strength gain in lime-fly ash mixtures begins only after a delay in time, which is due to the induction period for the reactions that take place between lime and fly ash particles. This research work studies this induction period using unconfined compressive strength (UCS) tests and differential scanning calorimetry (DSC) tests. Based on nucleation and diffusional growth theories, the induction period is qualitatively explained and the relevant equation for its quantitative prediction with regard to curing temperature is proposed. The suggested equation is evaluated using the UCS and DSC test results. It is concluded that the induction period can be predicted quantitatively and that accelerated curing can be used to estimate the induction period for any curing temperature. Furthermore, DSC tests can be used successfully for predicting the induction period.