This study developed a phenomenographic argument regarding science teacher educators' (STEs) question-asking conceptions. Question-asking in teaching how to teach science concepts to prospective science teachers is a fundamental strategy. However, STEs' conceptual understanding of the question-asking phenomenon is uncharted territory. The present study aimed to explore the STEs' question-asking conceptions based on complexity around a newly proposed classroom discourse-based conceptual taxonomy that can be used to think about what-aspects and how-aspects of STEs' question-asking. The participants were 29 STEs. The participants' experienced-based conceptions of question-asking were categorized as monological, declarative, dialogical, and dialectical in the outcome space. From a monological to a dialectical conceptual stance, the STEs externalized their question-asking conceptions by the following themes: questions are intellectual traps, questions are pre-organizers, questions should be used for control and evaluation, questions are feedback systems, questions are effective communicative tools, questions fluctuate students' cognition, questions ensure students' concept formation, questions are enacted for students' conceptual change, and questions are triggering for argumentative discourse. Finally, educational recommendations were offered regarding pedagogic noticing and professional development of STEs regarding question-asking.