My paper I've recently been working on, Property Rights and Contract Form in Medieval Europe, is now up on SSRN. Here's the abstract:

Throughout western Europe, beginning about 1200, leasing of feudal lords' estates became more common relative to direct management. In England, however, direct management increased beginning around the same time and until the fourteenth century, and leasing increased thereafter.

This article models the lord-peasant relationship as a game where contract form is chosen as the result of a tradeoff between incentives for high effort and excessive risk-bearing. Leasing increases as peasants' living standards improve. As for England, the increase in direct management can be explained by property law innovations that increased the security of freehold tenure, and the increase in leasing can be explained not only by improving living standards but also by increasing security of leasehold tenure. This model also explains why small landowners are more likely to manage their land directly, and why large landowners are more likely to lease their small estates than their large ones.

Feel free to download, read, and comment. You can get the article here. Also, the same goes for my other article, Privatization and the Law and Economics of Political Advocacy.

UPDATE: I apologize if the abstract is hard to follow. The 150-word limit (not for SSRN, but for certain journal submissions) is tough. "Direct management" and "leasing" are two alternative ways of managing one's estate. Also, I didn't realize that SSRN requires registration or membership to download papers. Write me an e-mail at volokh at post dot harvard dot edu asking for a copy of the paper, and I'll e-mail it to you.