This chapter summarizes the cycling of the elements in the environment and outlines open questions that need to be answered and opportunities for research. We briefly explain the need to reexamine biogeochemical cycles in the context of new knowledge, analytical and research techniques, and environmental challenges. Biological drivers of weathering, changes in elemental cycles as influenced by anthropogenic drivers, including climate change, and examples from frontier and managed ecosystems, which are more sensitive to human impacts, are discussed. Key themes from each chapter are outlined. The chapter is concluded with the list of topics and critical questions that book contributors believe need further study in order to improve our understanding of biogeochemical cycles as both environment and science evolve.