Agricultural diversification can occur in many forms (e.g., genetic variety, species, structural) and can be created temporally and over different spatially scales (e.g., within crop, within field, and landscape level). Crop diversification is the practice of growing more than one crop species within a farming area in the form of rotations (two or more crops on the same field in different years), multiple crops (more than one crop in the same season on the same field) or intercropping (at least two crops simultaneously on the same field). Various cropping strategies and management practices, such as diversification of cropping systems by crop rotation, conservation tillage, and the use of cover crops, have been promoted to enhance crop productivity and ecosystem services. However, the opportunities and means differ among regions and the actual effects of diversification on cropping system sustainability still need more investigation. This Special Issue covers the state-of-the-art and recent progress in different aspects related to agricultural diversification to increase the sustainability and resilience of a wide range of cropping systems (grassland, horticultural crops, fruit trees) and in a scenario of environmental challenges due to climate change: · Crop production and quality; · Impact of crop diversification on soil quality and biodiversity; · Environmental impact and delivery of ecosystem services by crop diversification.