Background: Physical educators are faced with trying to provide motivating and enjoyable experiences in physical education. Sport Education is an instructional model that aims to provide positive motivational sport experiences by simulating the features of authentic sport. Research support for Sport Education is positive, however, the effects on student motivation and the motivational climate are not well understood. Purpose: To investigate the influence of the Sport Education model on student motivation (intrinsic/extrinsic motivation, goal orientations, and perceived motivational climate) in secondary physical education. Setting: Six classes were selected according to teacher and class availability in the sports of soccer, hockey, and football codes in a co-educational government school. Participants: Participants were 115 (male = 97, female = 18) Year-8 students (aged 13-14 years), in a Sport Education condition (n = 41) and a Traditional condition (n = 74). Measures: At pre- and post-test, all participants completed three questionnaires: the Intrinsic Motivation Inventory, the Task and Ego Orientation in Sport Questionnaire, and the Perceived Motivational Climate in Sport Questionnaire. Intervention: Participants completed either a Sport Education condition or a Traditional condition for one double period (100 minutes) one day per week for 10 weeks (Sport Education condition) or for five weeks (Traditional condition). The Sport Education condition incorporated six distinctive features: seasons, affiliation, formal competition, record keeping, festivity, and a culminating event. The Traditional condition used whole-group instruction led by the teacher. Research design: The study used a non-equivalent control group design with pre- and post-test procedures. The independent variable was teaching condition and the dependent variable was student motivation (assessed by intrinsic motivation, goal orientations, and motivational climate). The groups were already established and selected for convenience purposes. Data collection and analysis: Participants completed pre-test measures and then participated in their pre-established classes. Post-test measures were completed in the last class in each condition. A reliability analysis on measures was conducted using Cronbach's alphas. A pre-test manipulation check was performed to check for any initial differences in motivation. To compare the difference in changes between conditions on motivation, a series of 2 x 2 repeated measures analyses of variance were conducted. A comparison of the relationship between motivation measures was conducted using Pearson's product moment correlation coefficients. Findings: There was a significant difference between the conditions on changes in perceived competence, task orientation, and mastery climate, with the Traditional condition decreasing significantly from pre- to post-test compared with the Sport Education condition. There were no significant differences on interest/enjoyment, effort/importance, pressure/tension, ego orientation, or performance climate. A mastery climate was positively related to task orientation and intrinsic motivation and a performance climate was related to ego orientation. Conclusions: The Sport Education condition was more successful in maintaining high levels of intrinsic motivation, task orientation, and mastery climate than the Traditional condition. That is, the Traditional condition was associated with a decrease in adaptive aspects of motivation for students, whereas the Sport Education condition maintained existing levels of motivation. (Contains 3 tables.)