There is much recent interest in the grain yield response of corn (Zea mays L.) to plant spacing deviation and plant emergence variation. More is known about plant spacing deviation than plant emergence variation. Key planting factors influencing corn stand establishment include spacing of seed, uniform seed depth, seed quality, planter speed, insects, diseases, desired seed population, and optimum soil environment for rapid germination and uniform emergence (including soil moisture and temperature), No single factor is responsible for differences among fields for stand establishment, rather fields with uneven plant spacing have unique problems and often a combination of factors during the planting operation leads to inconsistent stands.