Convicted sex offenders released from custody at the end of their criminal sentences pose a risk for re-offense. In many US states, Sexually Violent Predator (SVP) laws have been enacted that allow for the post-prison preventive detention of high risk sex offenders. SVP laws require the courts to make dispositions that protect the public from harm while at the same time respecting the civil rights of the offender. This book describes these SVP laws, their constitutionality, and aspects of their operation. Courts hear expert risk testimony based heavily on the results of actuarial risk assessment. Problems associated with this testimony include the lack of a theory of recidivism risk, bias due to human decision-making, and the insularity of scholarship and practice along developmental lines. The authors propose changes in legal standards, as well as a unified developmental model that treats sexual violence as an "evolving" condition, with roots traceable to childhood and paths that extend into adolescence and adulthood.