Every year, an international call solicits proposals for workshops from every field of the mathematical sciences and its applications. A proposals template requires a summary of the present state of the field, a discussion of the leading questions that motivate the proposal, and a justification for the timeliness and appropriateness of the workshop. A preliminary list of participants is also requested. The proposals have outnumbered the available spots by a ratio of 3:1, with no sign of let-up, in fact, quite the reverse, so the competition is strong and the committees are never short of excellent proposals to select from. All proposals are placed in a single data file that is made available to the members of the Scientific Advisory Board, who then make their comments online. In addition, the Scientific Director solicits additional reviews for particular proposals from outside experts, so that by the end of the process each proposal has had at least 5 reviews. The Program Committee then meets in November and makes its final selections.

At this meeting, the committee first reviews each category, linearly ranking the proposals within it. Then proposals are selected by running across the categories. In this way, a distribution across the mathematical sciences is maintained, to the extent that there are first-rate proposals in those areas. The BIRS Program Committee ranks proposals by scientific excellence alone, without regard for the geographical origin of the proposal.

The list of prominent mathematicians and scientists who have participated in BIRS activities is long and diverse. The competitiveness of the selection process makes sure that only the best and most pertinent scientific themes are chosen. A quick look at the people on the Scientific Advisory Board during the last few years of BIRS shows the exceptional quality that BIRS was able to attract. Their impeccable professional standards dictate the selection process and maintain the BIRS international reputation for research excellence. The excellence and the commitment of the organizers are also key criteria in the selection process. In return, the limited number of allowed participants forces the organizers to adhere to the highest standards. All these factors combine to make BIRS a unique centre of excellence, with a substantial scientific return on the investment by four governments.