This technical report presents the NATO Force Mix Analysis (NFMA), a collaborative study by the Atlantic Council and MITRE aimed at evaluating NATO's force design options for the Eastern Flank from 2025 to 2030. The report outlines the necessity for NATO to adapt its operational concepts and enhance defense capabilities in response to evolving geopolitical threats, particularly from Russia. It emphasizes the importance of data-driven analysis to inform investment strategies and improve multi-domain operations. The NFMA focuses on two key areas: enhancing NATO's targeting and lethality through a distributed multi-domain force capability, and strengthening regional capabilities in the Baltics. The analysis identifies potential force mix options that can provide effective deterrence and integrates contributions from Sweden and Finland. Key questions addressed include how to modernize NATO's posture, the most effective investments for rapid adaptation, and improvements to NATO's integrated fire networks. The findings aim to support NATO's strategic objectives and enhance collective defense.