Plant resistance inducers, also referred to as elicitors, are agents that confer improved protection to pathogen or pest attacks by inducing host defense mechanisms. Such products are effective against a wide range of crop enemies, including viruses, bacteria, fungi, oomycetes, nematodes, and herbivores. The mode of action of these products differs from that of traditional pesticides because they do not target directly the bio-aggressor through antifungal activity, but they inhibit its development indirectly via the elicitation of plant defense reactions. In the current context of sustainable agriculture and growing demand for healthy food, plant resistance inducers are considered as an eco-friendly and promising alternative to conventional pesticides, and their implementation in integrated pest management strategy is strongly encouraged. Plant resistance inducers can be of synthetic or natural origin. This chapter will focus on resistance inducers of natural origin including living microorganisms, plant extracts, microbial cell-wall extracts, microbial metabolites, minerals, and ions. An overview on the market and recent advances on the regulation of these products as well as future challenges to promote their development and wide use in disease management programs will be described.