In the United States, sudden cardiac arrest strikes nearly 1,000 people each day, and only 5% survive. However, the use of automated external defibrillators (AEDs) could potentially prevent 100,000 deaths per year. The potential for cardiac arrest to occur in athletic settings is well documented. Recently, the installation of AEDs in sport and recreation programs has increased, however, their implementation has not gained industry-wide acceptance. The purpose of this investigation was to examine the scope and nature of AED use in high school athletic departments. Based on a review of the literature, interviews with high school athletic directors, the use of focus groups, a test of content validity, and a pilot study, a survey form was developed to measure factors and constraints affecting implementation decisions for departments with and without AEDs. Measurement format included Likert scales, multiple choice, and open-ended responses. The survey was mailed to all high school athletic directors within a state. Follow up procedures were conducted and 269 completed forms were returned, representing a response rate of 47%. The majority of respondents were male (84%), over the age of 40 (64%), CPR (66%) and first aid certified (54%), represented public institutions (74%), and had worked in their current position an average of 8.5 years. Additionally, 38% of the respondents had administrative responsibilities for their school's physical education program and 16% were AED certified. Descriptive statistics, chi-square analyses, and one-sample t-tests with adjusted alpha levels were conducted. The number of programs that did not have AEDs (85%) was significantly (p < .05) greater than those with AEDs (15%). A total of 27 constraints that affected AED implementation were identified. The greatest constraints included the cost of purchasing an AED, cost of maintaining an AED, and a lack of information about protection from liability. Conversely, the weakest constraints were concerns over a lack of support from professional coaching association, a feeling that AEDs were not needed because CPR was adequate, and concern with a lack of support from insurance company. Given the importance of AEDs as lifesaving devices, the findings indicate inadequate AED usage in high school athletic departments and the need for educational and promotional efforts to enhance AED implementation. This study was funded by a grant from the American Heart Association.