and the Laboratory of Tree-Ring Research at the University of Arizona collaborated to host this fifteenth biennial conference to promote new ideas and directions in the archaeology of the US Southwest and the Mexican Northwest. Past symposia highlighted key research topics such as migration, mobility, demography, technology, identity, social change, ecology, interaction, connectivity, and regional archaeological cultures, to name a few. The 2010 Hermosillo symposium focused on archaeological practice and transnational archaeologies. The resulting volume (Villalpando and McGuire 2014) included papers on cross-border collaborations, public education and outreach, heritage management, and archaeological tourism. 2016 seemed the right time to revisit and expand that theme with special attention to collaboration with descendant communities, anthropologists beyond archaeology, and colleagues in the natural sciences.In this volume, based on the 2016 symposium, we again take the position that the way we practice archaeology shapes both our research questions and the results. Some archaeologists lament the current lack of unified theory in the discipline, as researchers draw from diverse theoretical and methodological toolkits to implement their projects. The choice to