Hi John,  Thanks for writing and for your interest in Credit-Aid Pro Software. Our Pro Software can handle up to 1000 clients (depending on which version you buy).  You can see detailed info and pricing at the bottom of this page:  www.credit-aid.com/pro.htm .  For further information, please call Barbara in our office for a free consultation.  She can answer all of your questions and help guide you in the right direction.  She can also tell you about specials.  You can reach Barbara toll free at 1-800-257-1192 extension 702.