Policymakers seeking to design efficient and smoothly functioning pension systems for their aging workforces are beginning to acknowledge the key importance of administrative expenses when formulating rules for pension plan structure and fee disclosure requirements. This study explores the links between retirement plan offerings and pension expenses for a wide range of private and public sector pension plan types, using an invaluable new data set on two thousand Australian pension funds. Our analysis indicates how pension plan design can strongly influence plan expenses and consequently eventual retirement security.