Two methods for estimating measures of pass-fail reliability are derived, by which both theta and kappa may be estimated from a single test administration. The methods require only a single test administration and are computationally simple. Both are based on the Spearman-Brown formula for estimating stepped-up reliability. The non-distributional method requires only that the test be divisible into parallel half-tests; the normal method makes the additional assumption of normally distributed test scores. Bias for the two procedures is investigated by simulation, using a Monte Carlo study. For nearly normal test score distributions, the normal method performs slightly better than does the non-distributional method, but for moderately to severely skewed or symmetric platykurtic test score distributions, the non-distributional method is superior. Test results from a licensure examination are tabulated to illustrate the methods. (Author/SLD)