Enhancing and maintaining on-farm diversity is a potential strategy to improve farming systems’ sustainability and resilience. However, diversification is driven or constrained by different factors and dynamics that vary across environmental, socio-economic and political contexts. Identifying drivers and constraints of diversification can help to support the adoption of on-farm diversification strategies, where doing so is beneficial. For the first time, we systematically review and summarise recent peer-reviewed studies assessing drivers and constraints of on-farm diversity from 42 different countries. From 2312 studies, we selected a total of 97, reporting 239 drivers and constraints, which we categorised using the Sustainable Rural Livelihood Framework. We extracted the number of times they were assessed as having a positive, negative or neutral relationship with on-farm diversity. Some factors mainly have a positive relationship, such as the need to adapt to risks or belonging to indigenous ethnicities, but for most of the others the results are mixed. Our major conclusions are as follows: (1) The adoption of diversification strategies is affected by both production and demand dynamics, with differences depending on farms and contexts; (2) small subsistence-oriented farms tend to adopt on-farm diversification strategies to cope with environmental characteristics and risks and satisfy their subsistence needs; (3) farmers may shift towards specialisation strategies if the comparative advantage of diversification and its natural insurance effect gets displaced by market opportunities, financial capital, technologies and the availability of alternative and more profitable sources of income; (4) the availability of technologies enabling farm diversification and the access to alternative market options are crucial to stimulate the implementation and maintenance of on-farm diversity; (5) future policies and research promoting the adoption of on-farm diversification strategies need to design mechanisms and incentives that consider the opportunity-cost of alternative livelihood opportunities, and that are suitable for the local context and for farmers’ objectives.

加强和维持农场多样性是提高农业系统可持续性和复原力的潜在战略。然而，多样化是由不同的因素和动力驱动或限制的，这些因素和动力因环境、社会经济和政治背景而异。确定多样化的驱动因素和限制因素有助于支持采用农场多样化战略，这样做是有益的。我们首次系统地回顾和总结了近期同行评议的研究，评估来自 42 个不同国家的农场多样性的驱动因素和制约因素。从 2312 项研究中，我们总共选择了 97 项，报告了 239 个驱动因素和制约因素，我们使用可持续农村生计框架对其进行了分类。我们提取了他们被评估为阳性的次数，与农场多样性的负面或中性关系。一些因素主要具有正相关关系，例如需要适应风险或属于土著民族，但对于其他大多数因素，结果喜忧参半。我们的主要结论如下：（1）多样化战略的采用受生产和需求动态的影响，因农场和环境而异；(2) 以自给为导向的小型农场倾向于采取农场多样化战略，以应对环境特征和风险，满足其生存需求；(3) 如果多样化的比较优势及其自然保险效应被市场机会、金融资本、技术和替代性和更有利可图的收入来源的可用性；(4) 使农场多样化的技术的可用性和获得替代市场选择的机会对于促进农场多样性的实施和维护至关重要；(5) 促进采用农场多样化战略的未来政策和研究需要设计机制和激励措施，考虑替代生计机会的机会成本，并适合当地情况和农民目标。