In Texas, a crucial element in a jury's deliberation on whether the death penalty is to be administered following conviction in a particular capital murder case is determination of the probability that the defendant would again commit criminal acts of violence that would constitute a continuing threat to society (prediction of dangerousness). Furthermore, the constitutional validity of the Texas procedure under the 8th and 14th amendments is called into question. The article argues that although Jurek v. Texas is dispositive of the facial validity of the Texas death penalty statutes, administration of those statutes is nevertheless subject to the constitutional standards laid down in Jurek and its companion cases. Thus, substantial evidence exists that practice under the Texas procedure violates the 8th and 14th amendments. The Texas experience reveals substantial practical deficiencies in the dangerousness inquiry that render suspect the product of the inquiry and call into question its general use as a basis for important legal decisions. The failure of the trial courts and the court of criminal appeals to resolve the ambiguities in the Texas dangerousness standard may have general significance. It suggests that those charged with administering a dangerousness standard may be reluctant to confront and resolve inadequacies in the standard, especially when the inadequacies provide flexibility useful in ignoring the standard in practice. Legislatures should carefully consider alternatives before adopting dangerousness as a legal standard, and courts should be hesitant about imposing it as a constitutional requirement. The article has 340 footnotes.