Coal as viewed microscopically is seen to be composed largely of discrete organic components referred to as macerals. Each maceral responds differently in carbonization, and each develops into a particular form of carbon in the coke product and has its own characteristic effects on coke microstructure. A classification of macerals has been developed and a number of correlations of this classification with coking behavior and coke properties have been established. Examples of how this classification serves in coal‐blend formulation and for predictive purposes are given. Basic knowledge about the chemical and physical constitution of coal and of the mechanisms involved in the response of coal to process conditions is stressed as a requirement in the development of new coke‐making technology.