How does a small advertising agency located way out in Bala Cynwyd, Pa., attract clients nationwide? It does something no other ad agency does: guarantees its work.

Gary Boens and Michael Aloisi, founders of Boens-Aloisi Inc., claim that the guarantee is an unorthodox strategy that is helping their $6-million (in billings) agency crack a tight market. Before accepting a new account, the two men sit down with the client and negotiate specific criteria upon which to judge the effectiveness of the ad campaign. Once both parties agree on the particulars, a guarantee is drawn up and incorporated into the regular contract.

The criteria are flexible, and can include sales increases, expanded distribution, or penetration of certain new markets. A typical guarantee, for instance, would stipulate that Boens-Aloisi is entitled to its full fee if the client's sales increase 10% during the ad campaign, half its fee if sales increase 5%, and no fee if there is no sales increase.

"We advertise our guarantee in newspapers and magazines, but a great deal of our business comes from word of mouth," says Aloisi, chairman and creative director. So far the agency hasn't missed a guarantee.