In recent years, the alarming increase of antibiotic resistance, compounded by the simultaneous decrease in development of new antibiotics, has created serious concerns for public health. Moreover, current antibiotics also target the beneficial commensal microbes (microbiota) that inhabit our body, sometimes with significant health consequences. The answer to the antibiotic crisis thus involves broad, creative efforts to develop new treatments for infectious agents. Here I discuss what can be learned from investigating microbial competition in vivo and how this knowledge can be utilized to devise new narrow-spectrum therapeutics that target bacterial pathogens while minimizing deleterious effects to the microbiota.