This study examines inservice elementary school teachers' beliefs, attitudes, and practical knowledge toward inquiry-based science instruction and the influence of an inquiry-based elementary science course on teachers' beliefs, attitudes, and practical knowledge regarding inquiry. Both surveys and a case study were administered to the 14 elementary school teachers before and after completing a three-credit elementary science methods course that was inquiry-based. The findings showed that the teachers' beliefs, attitudes, and practical knowledge about inquiry were clearly influenced by the course. Through this course, the teachers developed fairly positive beliefs and attitudes that promoted inquiry instruction. The majority of participants also improved their knowledge and skills of conducting inquiry as they successfully practiced inquiry-instruction in their science teachings.