New procedures are described for analyzing diffusion length measurements obtained by using several methods which, in the past, have shown inconsistent results. These procedures consist of a microwave photoconductive decay method and three techniques in which carriers, generated by &ggr; rays, 1‐MeV electrons, or ir light, are collected by ap‐njunction. Special attention is given to measurements of solar cells in which the sample thickness may be comparable to the diffusion length. A theoretical analysis of each method is presented, as well as the results of a study in which a set of solar cells with a wide range of diffusion lengths was measured. It is shown that results from all methods are consistent over the entire range. A discussion of the advantages and disadvantages of the various methods is also included.