Introduction: Learnability and Linguistic Theory.- Learning Theory and Natural Language.- The Plausibility of Rationalism.- On Applying Learnability Theory to the Rationalism-Empiricism Controversy.- On Certain Substitutes for Negative Data.- Markedness and Language Development.- Learning the Periphery.- Some Problems in the Parametric Analysis of Learnability.- From Cognition to Thematic Roles: The Projection Principle as an Acquisition Mechanism.- List of Contributors.- Index of Names.- Index of Subjects.