Organizing a congress is a project with a limited time span, which in many instances tequires substantial organizational and financial investments. Deadlines and related uncertainties make it often difficult to find financial support of a general bank. The University and the Municipality of Leiden established the Leiden Congress Fund. Congress organizers can appeal to the foundation for pre-financing1 and/or underwriting guarantees2. In principle everyone who organizes a national or international congress can apply for funding out of the Leiden Congress Fund under a number of conditions.