Buildings consume approximately 43% of their electricity for space heating and cooling, emphasizing the need for energyefficient solutions. Among the strategies to reduce this demand, phase change materials (PCM) have been recognized for their potential to enhance thermal performance. While PCM has been extensively studied in building envelopes, its integration with cross-laminated timber (CLT) remains unexplored. Additionally, the optimal placement of PCM within wall assemblies lacks consensus, as previous studies have reported inconsistent findings. This study addresses these research gaps by investigating the performance of PCM-integrated CLT (PCM-CLT) wall systems across 17 climate zones in the United States. Using EnergyPlus simulation, five wall configurations were analyzed, including three PCM-CLT configurations with PCM positioned at different locations within the assembly. The results demonstrate that the PCM-CLT system significantly enhances energy efficiency, achieving cooling energy savings of up to 72.48% and heating energy savings of up to 96.94% in certain locations. Moreover, the findings reveal that placing PCM on the interior side of CLT walls consistently outperforms other configurations across all climate zones. Furthermore, PCM-CLT walls help reduce peak energy loads, alleviating stress on power grids. This research contributes to enhancing building energy performance through PCM-CLT integration, providing valuable insights for both retrofitting and new construction, and advancing sustainable building design.