This study investigated how pre-service teachers' fractional concepts are related to solving problems involving advanced fractional knowledge. 96 Participants took a written test including three fractions questions about fraction concept, fraction comparison, and multiplicative relationship involving fraction quantities and composite units. The data were analyzed using an inductive content analysis approach. Findings suggest that many of our PSTs developed limited understanding of fraction subconstructs and thereby were not able to solve the three problems. Another finding is that when PSTs relied on only one sub-construct such as part-whole, they tend to provide incorrect answers. This finding implies that PSTs' understanding of fractions as measure and operator may be a foundation of solving problems involving advanced fractional knowledge. [For the complete proceedings, see ED583989.]