Calvinists... how do I know i'm one of the elect?

Take a look at the Heidelberg Catechism and see if those first few questions apply to you as one of the Elect. Your self-esteem has plummeted? Good. Then you realize who you are before God and why some people dress for church like they are going to court for their sentencing. And who Jesus Christ is and what he has done for you, setting you free from your sin.