Grain amaranth has a long and colorful history in Mexico. The historical use and the genetic diversity ofAmaranthus cruentusandA. hypochondriacuslandraces developed through the years make this country a prime area for research on and development of this crop. The first studies showed that native varieties had an acceptable yield, but these also demonstrated some unfavorable traits, such as excessive plant height, dark seed color, and a long growing season; therefore, a breeding program was established. A collection of landrace and nonindigenous germplasm was created. From the “Mercado,” “Nepal,” and “Mexican” morphological groups, outstanding selections were made for agronomic traits that permit yields over 2000 kg/ha, a growth season of 130 days, and plant height of 1.3 m, thus allowing mechanical harvesting. In addition, the most important pests and diseases were identified.