To hear Craig Brown tell it, midsize law firms are midsize for a reason. Their clients are local and regional. Their billing rates are lower. And truth be told, an attorney count around 100 feels just right to most of them.

So when it comes to expanding, these firms are extremely cautious. Brown, who gives presentations to gatherings of about 80 managing partners for the New York State Bar Association every quarter, says certain circumstances have to exist for midsize firms to branch out beyond their regional footprint.