Official labeling of phenomena that nurses diagnose and treat requires that researchers validate the existence of proposed diagnoses. One part of the validation process is the examination of content validity. The Delphi technique is a useful methodologic technique for such an examination. This article describes the characteristics, background, advantages, and disadvantages of the Delphi technique, as well as suggested strategies for using it to validate nursing diagnoses. In discussing strategies for using the Delphi technique to validate nursing diagnoses, the format, essential components, and steps of each round of the traditional and modified Delphi procedure are addressed. Round I of the traditional Delphi technique involves selection of a panel of content experts, developing and mailing questionnaires and content analysis, and generating a list of defining characteristics and operational definitions for a nursing diagnosis. Round II involves developing and mailing questionnaires, determining percentage of agreement, and providing statistical analysis. Round III includes developing and mailing questionnaires and providing statistical analysis of data. Round IV consists of developing and mailing the final report, which includes a statistical summary of individual and grouped responses in round III, as well as a minority report. The format and statistical analysis of the modified Delphi procedure is similar to rounds II, III, and IV of the traditional Delphi technique, except the modified technique usually will require only three rounds.