National Deposit Libraries usually own the largest collection of periodicals published in a specific country. This paper describes a method to study the coverage of periodicals in deposit libraries. The authors used two checklists to determine coverage of the periodicals collection in the Deposit Library of the Koninklijke Bibliotheek, the National Library of the Netherlands. Coverage was found to be circa 94 and 84 percent, respectively. The nature of the checklists and the selection criteria of the Deposit Library can affect results. These considerations should also be taken into account when comparing coverage among deposit libraries of different countries. Serials Review 2007; 33:40-44.