The assistant stage manager backs up the stage manager in a variety of ways, including taking messages and phone calls, communicating with the cast and crew and preparing to fill in for the stage manager when necessary.
The assistant stage manager helps the director, actors and crew with errands so they can focus on their jobs. He may assist the wardrobe designer, sound operator and lighting technician. The assistant stage manager must be flexible enough to do what's asked of him and change tasks when needed.
The Book is a journal kept by the stage manager that includes an audition form, contact sheet, production calendar, rehearsal schedule and report, blocking and cuing notations, pre-show check list and performance report. The assistant stage manager will learn the Book so she is able to run the show in the stage manager's absence.
The assistant stage manager is often situated just offstage to relay messages between the stage manager and actors. He may be called upon to help with quick costume changes or complex set changes.
There are often multiple assistant stage managers, necessitating teamwork. They must communicate clearly to ensure that all the bases are being covered and that they are not duplicating the work of another assistant stage manager. They must act as one entity so there is no confusion among cast and crew as they relay the desires of the stage manager and director.