The paper discusses the control of nitrogen oxide (NO-x) emissions from U.S. coal-fired electric utility boilers. NOTE: In general, NO-x control technologies are categorized as being either primary or secondary control technologies. Primary technologies in use in the U.S. are low NO-x burner (LNB) and overfire air (OFA). They utilize staged combustion to reduce NO-x formation in the primary combustion zone. Data reflect that primary technologies, applied on 177 boilers, have resulted in reductions of 33-48%, on average, from 1990 emissions levels. In particular, applications of LNB resulted in reductions of > 40%, on average, from 1990 level. Secondary technologies used on U.S. coal-fired utility boilers include reburning, selective noncatalytic reduction (SNCR), and selective catalytic reduction (SCR). Of these boilers, 14 have used, or will use, reburning as their No-x control technology. The NO-x reductions achieved, or expected to be achieved, at these boilers range from 39 to 67%. Of the U.S. coal-fired utility boilers, 22 have used, or will use, SNCR. NO-x reductions achieved, or projected, at these boilers range from 20 to 62%. Data indicate that 79 boilers will use SCR.