Consumer magazines occupy a unique position among U.S. advertising media. In total, they are a mass medium, yet taken individually, each carves out its own distinctive, selective audience. This selectivity is best delineated by primary readership, defined as those readers in households in which some member obtained the publication either through subscription or single copy purchase. Primary Readers are very different from Passalong Readers who come into contact with a publication through some means other than direct purchase. Different in terms of their involvement with the publication, different in terms of their reading behavior and different in terms of their response to advertising. The purpose of this paper is to place in clear focus the differences between the Primary and Passalong Reader and to demonstrate how an awareness of these differences can provide the basis for more efficient media and marketing plans.