Chapter 4 focuses on how ownership of immovables and movables are transferred (that is, whether registration is not needed, necessary, or creating opposability to third parties), whether registration creates absolutism (public faith principle), whether a real agreement is conceptually separate from a sale contract, and whether an invalid sale contract always leads to the invalidity of a real agreement (non-causa principle), and whether delivery or certain intentions are required to transfer ownership of personal properties or the sale contract itself is sufficient. This is where the traditional idea of legal families is conspicuous. Transfer doctrines involve how notice is given. The choice of registration system demonstrates how states, given path dependence, trade off transaction costs and third-party information costs. Which type of conveyance doctrine regarding immovables is efficient is contingent on factors outside of the law. It is easier to reform conveyance doctrine regarding movables, and lawmakers should provide alternative default rules (“menus”) more frequently and establish clear opt-out procedures (“altering rules”).