This paper presents a simple method for estimating a birth rate and a level of mortality for an intercensal period. The birth rate is estimated from the intercept of a line fitted to data and the level of mortality from the slope of that line. The formula that is developed is based upon a recent generalization of stable population relations. An estimate of childhood mortality level is an optional but significant piece of additional input. An important by-product of the procedure is an estimate of the true age distribution.