Empirical correlations for the prediction of drop size, dispersed-phase holdup, slip velocity, and maximum throughputs in packed columns are presented. Published experimental results obtained with both random and ordered packings are considered. The drop-size correlation, which is based on measurements from 376 runs with and without mass transfer from nine different sources for conditions when the continuous phase wets the packing, reproduces the data with an average absolute value of the relative deviation of 15.7%. A large bank of data (2023 points with and without mass transfer from 10 different groups of investigators; continuous-phase wetting; d(p) > d(p, cr) for random packings; phi < phi(f)) has been used to develop a correlation for the prediction of dispersed-phase holdup. The same body of data has also been used to derive a correlation for slip velocity without using holdup. By using the correlation for dispersed-phase holdup, the average absolute values of the relative deviation in holdup and slip velocity are 18.7 and 16.4%, respectively. The corresponding figures for the slip-velocity correlation are 20.1 and 15.6%, respectively. On the basis of data from 845 measurements with both continuous-phase and dispersed-phase wetting, an equation for maximum throughputs is derived which reproduces the data with an average absolute value of the relative deviation of 19.5%.