I love writing monologues, but it seems that in so many of today's contemporary plays, probably because of the heavy influence of TV, monologues are a dying art. Here are three reasons why monologues are great:
1. A monologue allows you to change the rhythm of a play. Your play may mostly be zipping along, with fast-paced dialogue, but sometimes you need to give the audience a chance to catch its breath or change things up. A monologue can do just that.
2. A monologue can take you to some other place or time without the need to build additional sets or create new scenes. A character's monologue can take you to the airport or the zoo or the last day of kindergarten or the day he lied to his best friend.
3. A monologue offers an opportunity to change the way the audience gets information. I'm not talking about a character telling you directly about herself. Not "I'm not the most popular person at school and I hate my hair and..." Instead, try having a character talk about something else entirely. It could be witnessing a man stealing ice cream or watching a kid bully another. In how the character tells the story about this other thing, how does that inform and develop the character? It's what we sometimes call "third-level dialogue," in that instead of the character telling us something directly, the sum value of the story is communicating that same information. It forces the audience to work harder and engage, and gives texture and variety to your play. Try it next time!