Since the Community Protection Act was passed in 1990 by Washington State, which allowed for the continued detainment of persons convicted of sexual offenses beyond their term of confinement, 19 other states, the District of Columbia, and the federal government have enacted similar laws (Mesler, 2016). Despite some variation across jurisdictions, the commonly referenced Sexually Violent Person/Predator (SVP) statutes include comparable elements: the person was convicted of a sexual offense; the person has a qualifying mental disorder; and the person is likely to engage in future acts of sexual violence. If a court determines that a person meets these criteria, they may be indefinitely committed to a secure facility until they no longer have a qualifying mental condition and/or is not likely to engage in sexually violent behaviors. Although the associated statutory language appears relatively straightforward, the application of these elements has generated an expansive body of case law to define and/or clarify how they should be interpreted. Whereas empirically derived psychological instruments and procedures to assess recidivism risk are adequate for most persons who engage in sexually harmful behaviors, there are special considerations when applying them within the SVP context. Specifically, the legal concepts included in SVP statutes do not directly translate into psychological constructs. This chapter will explore the current empirically based practice methodologies utilized to resolve these often-dissonant paradigms.