Perhaps the best-known plant and animal fossils are those that occur in rocks of Carboniferous (Mississippian and Pennsylvanian) age. The organisms that these fossils represent lived in the great coal-forming swamps that spanned a period of approximately 65 million years, beginning about 345 million years ago. There are two primary reasons why these organisms are known in such detail. First, the vegetation that contributed the plant material to the formation of coal was luxuriant and diverse. Second, the extensive mining of coal has provided paleontologists with a unique opportunity to discover organisms of this age that would certainly have not been unearthed were it not for the economic importance of coal. Thus, today it is possible to accurately characterize the Carboniferous fauna and flora from many geographic regions of the world. Although paleontology has traditionally been a rather descriptive science, in recent years the study of fossil organisms has become more biological in scope. For example, the life history of many fossil plants and animals is now known in great detail because of extensive collections that have provided an opportunity to investigate changes during the development of an organism. The study of pollination syndromes and reproductive biology (e.g., Taylor 1977) in certain plants and the spatial distribution (paleoecology) of plants and animals within the coal swamps (e.g., Phillips 1981, Scott 1979) are also rewarding avenues of paleontological research. One additional area that now t:an be seriously considered concerns the complex interrelationships of plants and animals that inhabited the coal swamps of the Carboniferous. In modern ecosystems a wide range of plant-animal interrelationships exist. Some of these are related to feeding, and many of the features associated with herbivory may have been the result of coevolution. Moreover, many plants have evolved complex defense mechanisms that may be both morphological and chemical. Clearly, an analysis of modern interactions can assist in better understanding the interrelationships deduced from the fossil record. In this paper interactions between plants and animals that lived during the Carboniferous will be discussed in the context of animal morphology, plant morphology, and coprolite analysis.