Research has long recognized that humans have many biases and shortcomings that severely limit our ability to accurately detect deception. How can we improve our deception detection ability? One possible method is to train individuals to recognize cues of deception. To do this, we need to create effective training curricula and educational tools. This paper describes how we used existing research to guide the design and development of a Web-based, multimedia training system called Agent99 Trainer to provide effective deception detection training. The Agent99 Trainer system integrates explicit instruction on the cues of deception, detection experience through practice, and immediate feedback with anytime, anywhere Web access. Our initial experiments show that our training improves human deception detection accuracy and the Agent99 Trainer system provides training as effective as instructor-led lecturebased training.