Cross-association is a standard correlation technique. It is valid for theoretically complete stratigraphic sequences, but not for stratigraphic sequences as they commonly occur. A major problem is its inability to include correlations across gaps caused by local nondeposition or eroded strata. The methods proposed in this paper do include correlations across gaps and allow for completely general measurements of strata similarity. In addition, they are extended to include correlation of a fragmentary sequence with a longer complete sequence and to include correlations of more than two sequences. Using these techniques, most problems can be handled by hand calculation. Correlation of stratigraphic sequences is an important problem. (In this paper, correlation is always used in the geological sense, not the statistical.) Stratigraphic sequences can be ob- tained from drill holes, outcroppings, or even road cuts. The data, in the simplest cases, are stratigraphic sequences of lithologic units, but may include much additional information such as strata thickness, geochemical or mineral assay, fossil occurrence and abundance, and electric, gamma, or gamma-gamma logs. A few elementary automated correlation techniques have been developed to utilize this information. The main one currently in use seems to have originated with Sackin, Sneath, and Merriam