Prostate cancer afflicts one man in nine over the age of 65 and represents the most frequently diagnosed cancer in American men (Coffey 1993). Early detection through serum testing for prostate specific antigen (PSA) and improved procedures for surgical intervention and radiation therapy have significantly reduced the number of fatalities; however, there is still no effective cure for men with advanced disease. Therefore, much research has been dedicated to identifying prognostic markers that distinguish indolent versus aggressive forms of prostate cancer. In contrast, significantly less research has been devoted to understanding the molecular mechanisms that underlie normal prostate growth and development or cancer initiation and progression. In this review, we address recent progress toward the central objectives of understanding parameters of normal versus abnormal prostatic development and of elucidating a molecular pathway for prostate cancer progression. We focus on key regulatory molecules that have been implicated by analysis of patterns of allelic loss in human prostate cancers and/or by reverse genetic approaches in the mouse.