Nearly all plants and animals form symbiotic partnerships with beneficial microbes. However, these symbioses don’t take place in a vacuum. Hosts are simultaneously attacked by parasites, pathogens, predators, and herbivores. My lab studies conflict between beneficial symbioses and defense against these antagonists. We use the mutualism between legumes and nitrogen-fixing rhizobia bacteria as our model system. Our research combines controlled inoculation experiments, fieldwork, and evolutionary genetics to understand the underlying mechanisms and evolutionary and ecological consequences of conflict between mutualisms and antagonisms. In my talk, I will share two stories from my lab’s research on conflict I host-associated communities. First, we’ve explored how root-knot nematodes, a widespread crop parasite, disrupt the rhizobia mutualism. Second, an emerging theme in our lab is how rhizobia jeopardize the production of a ubiquitous plant defense against herbivores: leaf defensive hairs. Our work implicates beneficial microbes as major mediators of the host’s response to infection and attack.