The statutory regime that governs employee benefit plans includes fiduciary provisions that track the obligations of loyalty and care developed in trust law. Relationships among key benefit plan actors, however, never have mapped neatly onto the trust law structure of settlors, trustees, and beneficiaries. In particular, the self-interest of the employers that sponsor benefit plans is in tension with their fiduciary obligations. Changes in the relative importance of some types of benefit plans have caused the tensions to become more acute. To address the relationships among benefit plan actors and the tensions between self-interest and fiduciary obligation, courts have developed implementing rules to adapt the fiduciary standards to the employee benefit plan ecosystem. This chapter compares two implementing rules to identify differences in the ways they function and have adapted to the current plan paradigms.