The role of a Stage Manager can not be defined in any hard-and-fast way as it varies from theatre to theatre and director to director, each one having their own particular requirements and ways of working. The following therefore is intended only as rough guidelines as it would be impossible to encompass the range of organisational demands of any given theatrical production.
The main role of S.M. is primarily to act as a link between the director and all the other areas of the production -- props, lighting, sound, publicity, prompt, costume designer, set design and construction, rehearsal facilities and also at times the actors and secondly to deflect some of the more mundane jobs and responsibilities from the director. The extent of an S.M.'s involvement in each of these areas varies according to the preferences of individual directors, but they are all areas in which he/she should expect some responsibility.
Having accepted the role of S.M. the initial contact is often in the form of a pre-rehearsal meeting with the Director, the Set-Designer, the A.S.M. and the people responsible for light, sound and costumes to establish the requirements of the play and discuss the set. Prior to this it is advisable to have read the play and made your own notes on the furniture and props required as a starting point for discussion. Try and get this list formalised by the end of your meeting so you have a definite idea of what is required. Check with the Director the requirements for the first rehearsal - how much of the set does he/she want marked out, which aspects of the set are felt to be essential and what his/her requirements are in the way of furniture and props for the initial rehearsals (although these will probably be substitutes to begin with).
Make sure you arrive in good time for rehearsals as you need time to check the set and props from the previous rehearsal before the cast arrives. This is also a good time to have a chat either with the director, other members of the backstage crew and the cast as they arrive about any problems that have occurred.
The first rehearsal is often a read- through so it is a useful time to get props and furniture organised for future rehearsals and get a rehearsal schedule worked out.Make sure you have a note of all the cast and crews availability and a contact number for them so that you can get in touch when the rehearsal schedule is altered, which it undoubtedly will be!
During rehearsals it is the responsibility of the S.M. to keep "THE BOOK" which consists of pages of the play interleaved with pages of plain paper on which you make a note of entrances and exits, moves, furniture and props, and eventually all the sound and lighting cues. It can be rather frustrating, as these are things which are constantly changing as the rehearsals progress, but as this is often the only complete record kept it is essential. This "book" is your only guide when the production starts and you take control of the backstage organisation of the play, so it is essential for it to be clear, accurate and complete.
The involvement of the person/people in charge of props varies considerably depending on the amount of props and the extent of their movement, but certainly towards the end of the rehearsal period they should be watching the rehearsal to get to know the play and what is required when it goes on stage: which side of the stage props appear from, who takes them on and off etc . If any of the cast have been found personal props make sure they take responsibility for them (or if in doubt collect them in at the end of each rehearsal!). Check with the director when (or even if) the prompt is required and contact them. Organise for the sound and lighting people to attend at least one rehearsal to get an impression of the play and talk to the director again about sound and lighting requirements, as these often change during the course of rehearsals. If photographs are being used in the publicity check with the director which rehearsal is the most suitable for the photographer to attend and let them know. Make sure that the cast are available for fittings etc. with the costume designers, in agreement with the director.
If any food or drink is required during the play then provide it during the final week or two of rehearsals as the cast need it for timing and to get used to using it.
Make sure you have a complete list of the cast and backstage team plus any one else who should be mentioned in the programme ( acknowledgements etc.) and give these to publicity along with the director's programme notes.
If there is to be any set-changing make sure you have a set-changing team for the technical and dress rehearsals and for the nights of the performance. If any set changing or movement of props is done by the cast, then make sure that the director organises this in rehearsals. If there is to be any set dressing discuss this with the director and if possible the designer and agree on what articles will be used.
During the last few rehearsals you need to co-ordinate the technical and dress rehearsals with the director and the back-stage crew. Make sure the set-builders, lights and sound people are given sufficient time to organise and check equipment before the actors arrive. Try and time a run-through of the play so you have some idea of its duration and the time of the interval(s); this information is often of use to bookings and front-of-house as well as the cast and crew. Make sure dressing rooms are allocated. Discuss with the director how the play will start and end - tabs, house lights, stage lights, sound etc. (And don't forget curtain calls!) Check that you have all the lighting and sound cues marked in the book.
Arrive in time to give the cast the 'thirty minutes to curtain up' call. Arrange with the front-of-house the signal for when you can start. Distribute some programmes for the crew and cast. Check that everyone is there before you start! Make sure there are no last minute problems back-stage and that everything is as and where it should be. The stage should be ready and clear of cast or crew before the audience is allowed in (usually thirty minutes before the performance begins). Give the cast 'time to curtain up' at regular intervals, and call beginners just before you start. Make sure the cast have time and access to a toilet at some point during the evening, and also that interval refreshments have been organised for everyone. At the end of the evening check that no plugs, lights, heaters etc. have been left on that should not have been.
During the actual performance you should be following the book and cueing lights and sound and making sure that the actors are there at the right time for their entrances, although all this is dependent on the type of production and the extent to which contact with other people is possible. You should also be checking any set changing and be aware of any problems as they arise (or even before if possible!) and try and sort them out so that they can be avoided in future.
When the last performance is over your final job, although not always such a minor one, is to ensure that all furniture and props get returned to their rightful home in one piece, and that the theatre and rehearsal rooms are cleared of any other items that have been used. After that, feel free to collapse in a heap - at least until the next production comes around!!