The study aimed at examining preservice elementary teachers' inquiry-oriented curriculum materials in an attempt to unravel their pedagogical design capacity (PDC) and pedagogical content knowledge (PCK) for inquiry-based learning (IBL), after attending a professional development program (PDP) centered around inquiry-based teaching and learning. In so doing, we identified the PCK for IBL dimensions (e.g., integration of inquiry within teachers' curriculum designs and evaluation of student learning) underpinning their curriculum materials and for each dimension, we aimed at finding the characteristics of the teachers' curriculum materials and capturing their PCK and PDC concerning that particular dimension. The participants were 44 preservice elementary school teachers enrolled in a PDP that was organized in four phases. In each phase, the teachers were assigned to a different role, namely, teachers as learners (Phase 1), teachers as thinkers (Phase 2), teachers as curriculum designers (Phase 3), and teachers as reflective practitioners (Phase 4). The data sources involved mainly teachers' curriculum materials that were analyzed with the use of grounded theory methodology and the constant comparative method. The data analysis revealed that the teachers' curriculum materials were developed along five PCK for IBL dimensions. Moreover, a number of characteristics of the teachers' curriculum materials were identified for each one of these dimensions, which in turn were clustered along three levels of increased sophistication and revealed our teachers' PDC per dimension. We also managed to identify three different PCK for IBL profiles. Finally, the findings indicate that, even though our preservice teachers attended our specially designed PDP, they have conceptualized in diverse ways the underlying principles of IBL.