Among the most striking details of the corporate era depicted in the AMC series Mad Men, along with constant smoking and mid-day drinking, is the army of secretaries who populate Sterling Cooper, the 1960s ad agency featured in the show. The secretary of those days has gone the way of the carbon copy and been replaced by the executive assistant, now typically reserved for senior management. Technologies like e-mail, voice mail, mobile devices, and online calendars have allowed managers at all levels to operate with a greater degree of self-sufficiency. At the same time, companies have faced enormous pressure to cut costs, reduce head count, and flatten organizational structures. As a result, the numbers of assistants at lower corporate levels have dwindled in most corporations. That’s unfortunate, because effective assistants can make enormous contributions to productivity at all levels of the organization.

A version of this article appeared in the May 2011 issue of Harvard Business Review.