A book of business refers to the relationship that an attorney has with existing clients and the list of names an attorney has who may be potential clients. When an attorney considers getting a job or starting his own firm, his book of business is key to determining his success. Such a concept exists in many industries — including accounting, public relations and other industries where relationships are of paramount importance — but the term book of business is most commonly used in a law firm setting.
Attorneys make money through representing various clients. These clients can be recruited in a number of ways. Attorneys may advertise on television or on billboards or other mediums. Alternatively, clients may approach an attorney or a law firm because of that firm's reputation.
Those lawyers who are excellent at generating new business are typically called rainmakers. Being a rainmaker is a positive attribute in an attorney and can help him be promoted within his firm. Those who make partner in a law firm, which is the highest level of promotion, are generally either rainmakers and/or have their own established list of clients.
As attorneys move through their careers, working with and representing individual clients, they begin to develop relationships. Some of these clients come to depend on an attorney and would work with that particular lawyer regardless of which firm he works with. These clients are extremely valuable to an attorney, since he can then consider striking out and starting his own firm with a built-in client base, or because he can find a job in a new law firm and get higher pay or better benefits since he is bringing his clients with him.
The list of clients who the attorney has a relationship with is considered his book of business. The term stems from the fact that those individuals the lawyer has worked with in the past will continue to provide him with business income. The larger an attorney's book of business is and the more potential clients he believes will continue to work with him, the more valuable the attorney is as a new hire. Typically, it takes at least several years for an attorney to develop the types of relationships that would inspire a client to stay with him instead of with his law firm. Thus, it can take years to build a large book of business.