The effect of the flipped classroom model (FCM) on high school students' science motivation and achievement in an urban public school was examined using a quasi-experimental pretest/posttest design. Over 4 weeks, sixty students engaged in the FCM and 62 students engaged in the traditional classroom model. Motivation was measured using the Science Motivation Questionnaire (SMQ-II), and achievement was measured using the Endocrine System Unit Test (ESUT). A statistically significant difference in students' composite levels of motivation when engaging in the FCM as compared with the traditional face-to-face model was found, with a statistically significant difference among the self-efficacy subscale only. A significant difference in academic achievement was not found. The implications of the research and suggestions for future examination are discussed.