A qualitative and quantitative study has been made of the Recent taxa assigned, or related, to Balanus amphitrite Darwin. All taxa of the complex have been redescribed and a key provided. Interspecific relationships have been evaluated statistically through the use of the generalized distance function and discriminant function analyses. Two well defined groups and three subgroups have been defined and a key proposed. The discriminant function has also been utilized as an aid in the identification of unknown specimens of a closely related pair of taxa.