Even for the most gifted individuals, the process of becoming a leader is an arduous, albeit rewarding, journey of continuous learning and self-development. The initial test along the path is so fundamental that we often overlook it: becoming a boss for the first time. That’s a shame, because the trials involved in this rite of passage have serious consequences for both the individual and the organization.

A version of this article appeared in the January 2007 issue of Harvard Business Review.