Inequality of opportunity, particularly when overlaid with socioeconomic, ethnic, or cultural differences, may limit the scope of cooperation between individuals. A central question, then, is how to overcome such obstacles to cooperation. We study this question in the context of Germany, by asking whether the propensity of immigrant youth to cooperate with native peers was affected by a major integration reform: the introduction of birthright citizenship. Our unique setup exploits data from a large-scale lab-in-the-field experiment in a quasi-experimental evaluation framework. We find that the policy caused male, but not female, immigrants to significantly increase their cooperativeness toward natives. We show that the increase in out-group cooperation among immigrant boys is an outcome of more trust rather than a reflection of stronger other-regarding preferences towards natives. In exploring factors that may explain these behavioral effects, we present evidence that the policy also led to a near-closure of the educational achievement gap between young immigrant men and their native peers. Our results highlight that, through integration interventions, governments can modify prosocial behavior in a way that generates higher levels of efficiency in the interaction between social groups.

机会不平等，特别是当与社会经济、种族或文化差异叠加时，可能会限制个人之间的合作范围。那么，一个核心问题是如何克服这些合作障碍。我们在德国的背景下研究这个问题，通过询问移民青年与本地同龄人合作的倾向是否受到重大融合改革的影响：引入与生俱来的公民身份。我们独特的设置在准实验评估框架中利用来自大型实验室现场实验的数据。我们发现该政策导致男性而非女性移民显着增加了对当地人的合作。我们表明，移民男孩之间外群体合作的增加是更多信任的结果，而不是反映了对当地人更强烈的其他方面的偏好。在探索可能解释这些行为影响的因素时，我们提供了证据表明该政策还导致年轻移民男性与其本国同龄人之间的教育成就差距几乎缩小。我们的结果强调，通过整合干预，政府可以改变亲社会行为，从而在社会群体之间的互动中产生更高水平的效率。