The goals of this volume are twofold: on a general level the volume explores whether evidence for teaching and learning can be found in mother-child interactions during the course of first language acquisition and whether these processes can be objectively described; on a sublevel, the volume investigates whether the denials of frequency and reinforcement effects found in the literature withstand closer scrutiny. The findings support a teaching/learning approach to first language acquisition and demonstrate some of the major principles involved in this process.