This chapter discusses efforts from a number of groups that lay the groundwork for an in vitro approach to study the population coding. Most researchers studying population coding are working with intact, living animals. The cultured neuronal networks lack many features of real brains, but they retain many others. They develop organotypic synaptic connections and exhibit a rich variety of distributed patterns of electrical activity. Progress in multi-electrode array technology, optical recording, and multi-photon microscopy, made it possible that every cell in a cultured monolayer network can be observed, monitored, stimulated, and manipulated with temporal resolution in the sub millisecond range, and spatial resolution in the submicron range, in a non-destructive manner. The nascent field of population coding in networks of cultured neurons is poised for rapid expansion. Neural cell culture, long-term multi-electrode recording and stimulation, and multi-single-unit optical recording are now accessible to many labs. Computers are fast and cheap enough to allow real-time spike analysis and stimulus generation, which makes it possible to give cultured networks a simulated body to behave with, and an environment to interact with. By allowing the culture to behave and receive sensory input, meaning can be ascribed to the patterns of electrical activity it produces, and persistent changes in network activity can be thought of as learning.