This study examined the impact of action research conducted by five science teaching methods course instructors on their students' perceptions of the classroom learning environments at a large public university in Texas. The study analyzed the results from 133 students who completed two administrations of the What is Happening in this Class (WIHIC) questionnaire, one at the beginning of the semester and one at the end of the semester. Five sections served as a treatment group while two sections served as a control. Quantitative analyses, including one-way ANOVA, were conducted for each class section. Results showed that the perceived learning environment increased between the beginning of the semester and the end of the semester for all sections. However, the most significant gains in students' perceptions were made in the treatment sections and were attributed to the action research interventions that were designed and implemented by the instructors based on the analyses of the first WIHIC administration.