The paper is an attempt to apply best taxonomic practice to a well delimited group of Foraminifera: the lagenids. Analysis results in the recognition of 20 characters.. which are defined and described through an explicitly defined, consistent terminology. The database resulting from the scoring of characters of all the lagenid genera allows the construction of a set of identification keys and the production of a set of uniform, consistent diagnoses. J. Micropalaeontol. 24(2): 145-158, October 2005.