Helping novices learn to facilitate interactive whole-class discussions is an important "high-leverage practice" for becoming an effective teacher due to its strong potential to increase students' learning opportunities. A semester-long classroom-based assignment in a senior-level elementary literacy methods course supported preservice teachers in developing the practice of leading one text-based interactive literary discussion, along with learning to establish norms and routines for discussions, and to analyze instruction for the purpose of improving it. Analysis of 83 preservice teachers' written work investigated their learning during the beginning stages of developing the complex practice of leading discussions. We propose a learning trajectory outlining three areas of development that may offer direction for helping preservice teachers improve in specific areas and provide a focus for future research.