Weed infestations cause an economic loss of $13 billion per year even though $9.5 billion per year is spent on weed control measures. In addition to these economic costs, weeds are replacing native species, altering native plant and animal communities, affecting ecosystem health and function, threatening biodiversity and Threatened, Endangered, and Sensitive (TES) species, altering fire behavior and fire regimes, and reducing wildland productivity. This paper discusses (1) where weeds are found, (2) what promotes weed invasions, and (3) how to incorporate weed management into fuel treatment activities.