One of the most intriguing consequences of climate change is altered timing of biological events (phenology). Ecologists have compiled long-term data sets to suggest that the timing of spring green-up is advancing earlier into spring as the planet warms and many species are beginning biological activity such as emerging from winter states and migrating earlier in the spring. Not all species, however, are capable of responding to warming to the same degree because not all seasonal activities are strictly tied to temperature, hence phenology advancement rates differ among species. Since many species rely on each other in mutualistic or predatory relationships, altering phenology at different rates in each actor can lead to phenological mismatch or disruptions in the timing of key interactions between species. These mismatches have been studied for ca. two decades and have been implicated in reduced survivorship or fecundity, processes that operate at the population level. Less well studied are the implications of phenological mismatch at ecological scales beyond the population. Yet, where examined, these mismatches have been demonstrated to have consequences in communities and for ecosystem functions. Our goal for this session is to bring the broader consequences of phenological mismatch to the attention of the larger ecological community at ESA. The first objective is to assemble a key group of researchers to present their work on community and ecosystem level consequences of phenological mismatch. For these talks, each researcher will answer two questions: first, what consequences have been observed in communities and ecosystems, and second, what is the best way forward in studying the larger implications of mismatch. The second objective is to develop collaborations toward synthetic research on mismatch and its consequences leading to a submitted paper following the symposium. This symposium will potentially be of interest to community and ecosystem ecologists and anyone interested in some of the lesser understood, but potentially large, ecological consequences of climate change.