This action-based research examines the relationship between collocation and speaking in L2. A four-month weekly speaking course was designed for university students in Japan and 72 students practiced speaking English using bigrams from the coursebook. Words and collocations spoken in a picture-description task were counted and then the knowledge of collocations and the students’ mental attitude were surveyed. A statistical analysis reveals a significant correlation between speech fluency and activated collocations and between speech fluency and positive attitudes towards speaking and collocation exercises. This result supports some recent studies of bigrams enhancing L2 speaking fluency. Future courses require better ways to test the learners’ collocation knowledge and ease their anxiety about speaking.