How do I know if the theatrical agent I am interested in is legitimate?

How do I know if the theatrical agent I am interested in is legitimate?

Agents are all signatory with a particular union. Here in the States we have Actors Equity which represents actors on the stage, the Screen Actors Guild which represent people in film and television, and also the American Federation of Radio and Television Artists that represents actors in film and television and other industrial type videos. These unions will all have an agent that will be a signatory of that union. They can let you know if an agent is legit or a reputable agency. You can also find out by referrals, if you have friends that are actors that you would like to emulate in some way, then you can speak to them and say, "hey look, what is this agency all about? Are they really able to help you? Do you think that they could help me?" These are types of questions you could ask any type of union representative as well.