Collectively, the LTER community is well positioned to address many of the overarching questions in community ecology regarding how ecological context can influence the community assembly mechanisms underlying observed biodiversity patterns. Because the metacommunity concept integrates local (e.g., biotic interactions, niche-based species sorting) and regional (e.g., biogeography, regional colonization histories) factors, it has the potential to serve as a framework to synthesize biodiversity patterns across ecosystems and taxa represented in the LTER network. This working group has three objectives: (1) Introduce our metacommunity modeling approach developed with support from the LNO and demonstrate how we have applied it to interpret biodiversity patterns at the BES and MCM LTER sites, (2) identify specific questions and challenges that the LTER community is uniquely suited to address in a cross-site metacommunity synthesis, and (3) develop a working plan and a proposal to submit to NSF for a follow-up workshop to move forward with the synthesis project. The working plan will summarize LTER data sets and quantitative approaches that are identified by the working group as crucial for understanding biodiversity pattern across the LTER network.