Traditional pension schemes, whether social security systems or occupational pension schemes, generally follow one of two design logics: either a Defined ContributionDefined Contribution (DC) scheme, where the level of contributions to be paid by the generation of active workers is explicitly defined; retirement benefits are derived by actuarial equivalenceActuarial equivalenceActuarial equivalence; or a Defined BenefitDefined Benefit (DB) scheme, where the level of retirement benefits to be paid is explicitly defined; the level of contributions is also derived by actuarial equivalenceActuarial equivalenceActuarial equivalence. Defined Benefit schemes can be considered as mechanisms where the risks are essentially borne by the contributors to the scheme; in contrast, in Defined ContributionDefined Contribution schemes, the risks are shifted to the beneficiaries of the scheme. To avoid this dichotomy, hybrid schemes have been developed, with an intermediate logic between Defined BenefitDefined Benefit and Defined ContributionDefined Contribution, in order to better share the risks between the parties. The objective of this chapter is to study this hybrid scheme logic in a Pay-As-You-Go environment. In particular, we present the Musgrave rule, which is intended to be an intermediate between DB and DC and which aims to guarantee a constant benefit ratioBenefit ratio net of contributions. Other intermediate schemes between DB and DC will also be presented. In the case of social security schemes, the ultimate aim is to share risks between generations (working people and retirees) in order to achieve greater inter-generational equity.