The chem­istry of nitro­gen is inex­tri­ca­bly linked with humanity’s use of ener­gy. Indus­tri­al nitro­gen fix­a­tion (N2 NH3) rev­o­lu­tion­ized the pro­duc­tion of fer­til­iz­er and enabled the pop­u­la­tion explo­sion of the 20th cen­tu­ry, con­sum­ing sev­er­al per­cent of the world’s ener­gy annu­al­ly in the process. NOX reduc­tion (NOX N2) is inte­gral to reduc­ing the adverse impacts of auto­mo­bile use on urban air qual­i­ty and health. These and oth­er suc­cess­ful tech­nolo­gies all depend at their heart on het­ero­ge­neous catal­y­sis. In this pre­sen­ta­tion, I will dis­cuss the insights we have gained by apply­ing mol­e­c­u­lar-lev­el mod­els and con­cepts to nitro­gen cat­alyt­ic chem­istry. Exam­ples will be drawn from our work on the selec­tive cat­alyt­ic reduc­tion of NOX, a prob­lem that has led us to rethink the fac­tors that gov­ern reac­tiv­i­ty in zeo­lites, from NO and NH3 oxi­da­tion, prob­lems that have caused us to revis­it how we mod­el reac­tions at met­al sur­faces, and from N2 reduc­tion, where we are explor­ing the poten­tial to bypass the con­straints imposed by moth­er nature on the per­for­mance of con­ven­tion­al cat­a­lysts.