Objective To determine whether the American Society for Parenteral and Enteral Nutrition (ASPEN) standards of practice for nutrition support dietitians reflect current practice. Design A mailed survey questionnaire was used to determine how important nine functions of the nutrition support dietitian are to the practice of nutrition support dietetics, how important the ASPEN standards are to practitioners, the frequency of application of each standard to patients, and demographic data of the respondents. Sample The survey was sent to 1,048 randomly selected dietitian members of The American Dietetic Association's Dietitians in Nutrition Support dietetic practice group and ASPEN. The final sample included 460 dietitians, a return rate of 44%. For purposes of comparison, dietitian respondents were categorized into three groups: nutrition support dietitians (n = 286); non-nutrition support dietitians (n = 136); and supervisors of nutrition support dietitians (n = 38). Statistical analyses performed Descriptive data are reported as frequency or mean +/- standard deviation. Differences in importance ratings of the standards by nutrition support dietitians, non-nutrition support dietitians, and supervisors of nutrition support dietitians were compared with one-way analysis of variance ANOVA and Scheffe post hoc tests. Chi2 Analysis was used to compare group differences in the frequency of application of each standard to patients. Probability was set at the .05 level. Results Nutrition support functions rated as very important included performing nutrition assessments, identifying high-risk patients, implementing and monitoring parenteral and enteral nutrition, supervising transitional feeding, and documentation. The standards of practice were all rated as very important by nutrition support dietitians, non-nutrition support dietitians, and supervisors, and there was no difference in perceived importance. More than half of the respondents applied each standard with 75% to 100% of their patients; however, there was a higher frequency of application by nutrition support dietitians. Applications/conclusions The findings give validity to the standards of practice. Practitioners evaluate them as being important in practice and in theory. The standards of practice for nutrition support dietitians were approved for use by the House of Delegates of The American Dietetic Association in October 1992.