Informal institutions govern property rights and disputes when formal systems are weak. Well-functioning institutions help people reach and maintain bargains, minimizing violence. Can outside organizations engineer improvements and reduce violent conflicts? Will this improve property rights and investment? We experimentally evaluate a UN and civil society mass education campaign to promote alternative dispute resolution (ADR) practices and norms in rural communities, where violent land disputes are commonplace. Prior work showed a fall in violence and unresolved disputes within a year. We return after three years to test for sustained impacts and channels. Treated communities report large, sustained falls in violent disputes and a slight shift towards nonviolent norms. Treated residents also report larger farms, though overall effects on property rights and investments are mixed. Politically-connected residents report more secure property rights while those with fewer connections feel less secure. Sustained social engineering is feasible but politics can shape distributional outcomes.