The land question.

One of the central claims of development economics is that insecure property rights inhibit investment. If you don't know whether the land will still be yours next year, you won't plant trees or build irrigation channels or take the long view on soil health. The expected return on any improvement that takes years to pay off collapses when tenure is uncertain.

The solution, in theory, is straightforward: give people legal title to what they already possess. Formalize the informal. Turn social arrangements into legal documents.

Rwanda ran the largest systematic land registration program in Sub-Saharan Africa between 2009 and 2013. It registered approximately 10.4 million parcels of land across the country — effectively the entire country. A research team from the World Bank used the randomized rollout sequence to evaluate what happened when formal title arrived.

What the evidence says

The Rwanda evaluation found what property rights theory predicted: investment in soil conservation went up. Specifically, investment in erosion prevention — building terraces, planting grass strips along contours, maintaining drainage channels — increased by 6.1 percentage points in areas that received formal title. This is not a trivial activity. In a country where soil erosion is a serious agricultural problem, terracing and conservation practices require labor investment that pays off over years, not months. Farmers who weren't sure the land would still be theirs had less reason to do it.

Land rental markets also became more active. Before formalization, informal land transactions were common but insecure — and lenders couldn't use land as collateral because title didn't exist. After formalization, land could be pledged, rented out formally, and transferred with legal protection. The rental market thickened.

The most consistent and striking effect was on women. Rwanda's land law required that titles register both spouses. Before formalization, women's land rights depended entirely on marriage and community norms — arrangements that offered no protection in case of divorce, death, or abandonment. After formalization, a woman's right to her household's land appeared on a legal document, registered with the government, with both her name and her husband's name on it. Courts could enforce it. The property rights gain was more durable for women than for men, because men's rights had been somewhat more secure under informal norms.

Where the theory was complicated

The Rwanda evidence confirmed the investment effect — but it also raised questions about the mechanism and the limits of formalization.

Property rights theory predicts that secure tenure increases investment because it improves the expected return on long-run improvements. Rwanda confirmed this. But the theory also predicts that formalization should increase access to credit — because land can serve as collateral for loans. This effect was smaller and more mixed in Rwanda. Formal banks remained difficult to access for small farmers regardless of title status. The credit channel, which figures prominently in theoretic accounts of why property rights matter, produced limited evidence of activation.

The theory also implies that formal title resolves land disputes. Rwanda's experience was more complicated: formalization resolved some disputes and created others, particularly in areas with complex inheritance histories or where community boundaries were ambiguous. Formal title is only as clear as the boundary it documents, and Rwanda's land landscape — shaped by colonial interventions, post-genocide resettlement, and rapid population growth — had boundaries that were contested in ways that written documents couldn't fully resolve.

The more important finding

What the Rwanda evidence contributes most clearly is a sense of what formalization can and cannot do on its own.

It can strengthen tenure security for currently uncertain claims. It can enable market transactions that informal arrangements block. It can give women formal standing in legal systems that previously recognized only male heads of household. It can create the minimum precondition for long-run investment where that precondition was absent.

It cannot, on its own, create access to credit markets, resolve deep historical land disputes, or substitute for agricultural extension services that help farmers act on secure tenure. The investment effect in Rwanda was real — but it was investment in conservation practices that farmers already knew how to do and already had the tools for. For investments that require knowledge, capital, or new inputs, secure tenure is necessary but not sufficient.

The economists who pushed hardest for property formalization in the 1990s and 2000s — de Soto's "mystery of capital" thesis, in particular — argued that title would unlock credit and transform poor farmers into market participants overnight. The experimental evidence is more modest: title helps, meaningfully, on the dimensions the Rwanda study measured. The transformational claim requires additional enabling conditions that title alone does not provide.

What this means for program design

For practitioners designing land policy in low-income countries, the Rwanda evidence suggests a few things.

First, systematic formalization is preferable to selective formalization. Programs that title some plots and not others create new inequalities and may generate conflict at the boundary. Rwanda's nationwide approach avoided this problem.

Second, formalization works better for women than for men in contexts where women's customary rights are insecure. The gender dimension of land formalization programs is often the most consequential and the least measured. Rwanda's requirement that both spouses appear on title should be standard practice, not an afterthought.

Third, the credit channel may not activate without parallel financial sector development. Expecting title to unlock credit from commercial banks that don't serve rural areas is expecting formalization to do more than it can.

The land question is a question about what makes investment worthwhile. The experimental evidence says: secure tenure helps. It does not say: secure tenure is enough.