One of the more notable features of Indonesian Islamic law is its recognition of the concept of jointly owned marital property. The Indonesian doctrine of joint marital property bears a striking similarity to the community property system in California. In both systems the marital estate consists of property acquired during the marriage through the efforts of either of the spouses. Both systems distinguish marital property from separate property and both define separate property as all property owned by either spouse prior to the marriage or acquired by gift or inheritance afterwards. Apart from their doctrinal similarity, Indonesian Islamic marital property and California community property are alike in another respect: Both are transplanted elements existing in foreign legal environments. Indonesian marital property is an indigenous Southeast Asian practice in an Islamic conceptual structure, while community property is a continental civil law institution in an Anglo-American common law system. In both cases, moreover, the conception of marriage that underlies the doctrine of joint marital property is out of harmony with the understanding of marriage reflected in the system's treatment of marriage generally. This Article compares the process of incorporation of joint marital property in Indonesia and California. The results of this comparison contradict the assumption that sacred legal systems are inherently less capable of change and adaptation than secular systems. Focusing first on California, it is shown that a fully egalitarian system of joint marital property did not emerge until the 1970s, more than 100 years after the civil law doctrine of community property was formally adopted in the state constitution in 1849. In Indonesia, by contrast, the indigenous customary concept of marital property encountered relatively little resistance from Islamic authorities. By analogizing household economic production to a commercial partnership, Islamic jurists were able to embrace joint marital property by recasting the doctrine as an Islamic institution.