This study examines how inherent contradictions affect supply chain planning (SCP) practices in engineer-to-order (ETO) settings through a multi-case study of five companies. The research identifies sixteen contradictions across four paradox categories: performing, organizing, belonging, and learning paradoxes. The findings reveal that contradictions shape SCP practices while SCP practices simultaneously influence how contradictions are managed. Companies employ four management strategies: acceptance, spatial separation, temporal separation, and synthesis to handle contradictions. One of the approaches acknowledge contradictions as inherent features of ETO settings rather than a problem to eliminate. Companies with structured SCP processes demonstrate better contradiction management capabilities, creating virtuous cycles of continuous improvement. The research contributes to paradox theory by validating the dynamic equilibrium model in SCP contexts and identifying organizational capabilities that enable effective paradox management. For practitioners, the study suggests that explicitly acknowledging contradictions, aligning organizational structures, and developing balanced performance metrics can transform competing demands into sources of competitive advantage rather than operational constraints.