Pedagogical reasoning, as one of the major components of teacher knowledge base, is crucially important in teacher education. Motivated by the dearth of research in this area, this study investigated the pedagogical reasoning of four novice language teachers in relation to speaking instruction in order to further our understanding of language teacher cognition. For this purpose, a qualitative approach was adopted and classroom observations and post-observation stimulated recall interviews were conducted over a period of eight months. The analysis of the data related to pedagogical reasoning episodes and reasoning complexity indicated that novice teachers employed varied pedagogical arguments for different aspects of teaching speaking to justify their pedagogical decisions, which included instruction-based, students-based, teacher-based, and context-based arguments. The findings also pointed to the developmental changes in terms of the complexity and comprehensiveness of novice teachers' pedagogical reasoning. Although they initially tended to focus primarily on the subject matter and instructional activities, their reasoning gradually expanded to include students' cognitive and affective characteristics. The findings of this study contribute to the research on the teacher knowledge base and cognition. Having a clear understanding of novice teachers' pedagogical reasoning and how they utilize it to explain their classroom practices provides us with valuable insights into the process of learning to teach.