Sport innovation is defined as an idea for doing sport in a way different from what it used to be done. The diffusion studies on innovations like this will provide valuable aids for sport administrators or marketers who are concerned with how to launch new sport services most efficiently. The theoretical purpose of the investigation was to analyze and describe the mechanism through which a sport innovation must pass before it is accepted. Operationally stated, the objective of the present study was to examine variables determining the rate of adoption of swimming school, a new form of educationing children which has grown from 1970's to 1980's in Japan, by clarifying the relationship between certain background variables of a new sport consumption behavior among the parents and their length of the innovation-decision period. Shortening the innovation-decision period is one of the main methods of speeding the diffusion of an innovation. The findings are based on a sample of 306 parents with the schoolchild who is attending swimming school selected from elementary schools in Fukui Prefecture. The data were collected by administering a questionnaire comprising items representing the operational definitions of the variables. All data were collected in the spring of 1986. The statistical techniques employed were factor analysis, multiple regression analysis and discriminant analysis. The main results are summarized below: 1) The parents who have been involved in sport under the favorable conditions during their childhood, can shorten the time required to pass through the decision process about sport innovation. On the other hand, the less favored parents require a longer innovation-decision period. 2) The parents who have a longer innovation. decision period are more highly interconnected in the communication networks than those who have a shorter innovation-decision period. 3) The degree of utilizing channels of communication or credibility in these sources is likely to be closely connected with the parents who have a longer innovation-decision period. This study was supported in part by a research grant from the Ministry of Education in Japan.