Consider copyright issues. If the book you wish to adapt is not in the public domain or one that you have permission to reproduce, an adaptation will violate the author's copyright. Visit Project Gutenberg (www.gutenberg.org) for a listing and complete e-texts of classic public domain novels.
Choose a story that is well-suited for the stage. If the story is set in multiple locations, a stage production will require numerous sets. Stories that take place in a single location are best suited for the theatre. Special effects and elaborate costumes are expensive to create. If the storytelling can be successfully accomplished through dialogue and visible human action, it may work well as a play. Narrators are not common in modern dramatic works.
Re-imagine the story. Follow the novel's plot and envision each scene as it might take place on a stage. Be prepared to make changes in the action to make it feasible in the constraints of a theatre.
Determine which aspects of the story's exposition can be included in the program notes. The setting and certain character details are traditionally included here, making your job as a playwright easier.
Decide how much of the novel's dialogue you want to keep. Unless you find the author deficient in the writing of good dramatic dialogue, it is best to retain as much original dialogue as possible. You may wish to update the language for the sake of modern audiences' understanding by removing or rephrasing antiquated terms. Be sure to retain any famous quotations that your audience would expect to hear. For example, Ebeneezer Scrooge must exclaim, "Bah! Humbug!" at least once.
Write additional dialogue. There are places in novels where key plot and character elements are revealed through a character's thoughts. You must find ways to communicate this information through action and dialogue. Actors can portray emotion, but logistical details must be concretely revealed. Avoid having characters speak their thoughts except in situations where it is plausible for them to do so. Instead, engineer reasons for them to relay this information in conversations with other characters. For example, if the novel contains a crucial line about a character noticing a certain smell, have him turn to another character and say, "Do you smell that?" You could also write a stage direction for the actor to pause and sniff the air with a puzzled expression.
Give your play a sit-down reading. In this process, actors sit in chairs and read their characters' lines while an additional speaker reads the stage directions. This is an effective way to test your play for cohesiveness and quality before staging the physical action.