The balance between photosynthetic carbon dioxide (CO2) assimilation and respiratory CO2 release influence plant growth, crop yields, and the ability of terrestrial ecosystems to offset ~2-3 Gt CO2 yr -1 of anthropogenic emissions. Rising atmospheric CO2 concentration ([CO2]) this century will impact plant photosynthesis and respiration with consequences for plant productivity in natural and agro-ecosystems. The capacity of all plants to grow and ecosystems to store carbon in elevated [CO2] can be dependent on interactions with water, nutrients, and plant developmental processes. The purpose of this thesis is to address fundamental knowledge gaps in understanding plant responses to the interaction between elevated [CO2] with water, nitrogen (N), and leaf developmental programs: (1) determine what is the mechanistic response of maize C4 photosynthesis to a three way interaction between atmospheric [CO2], N availability and drought utilizing the unique capabilities of a Free Air CO2 Enrichment (FACE) field experiment; (2) determine the transcriptional reprogramming of leaf respiration in response to growth in elevated [CO2] and variable N supply using Arabidopsis thaliana and a custom built gas exchange system; (3) determine when in leaf development the transcriptional reprogramming of respiration occurs in response to elevated [CO2] by studying the detailed developmental timelines and molecular events of leaf growth in A. thaliana. The knowledge gaps addressed in this work will help inform crop improvement and models that predict future ecosystem function and global food supply in the face of a changing climate.