Abstract
1. Introduction
2. Theoretical Issues
2.1. The Status of the Explicit/implicit Distinction
2.2. Explicitness and Implicitness in SLA
2.3. Interface Hypothesis
3. Empirical Evidence for Interface Hypothesis
3.1. Studies with Implicit Types of FFI
3.2. Studies with Both Explicit and Implicit types of FFI
3.3. Studies with Explicit Types of FFI
4. Discussion and Conclusions
References