Contents. 1. Introduction. 2. The labile phase in memory. 3. Changes in speed of consolidation. 4. The growth, shunt, and mode hypotheses. 5. State-dependent learning. 6. Possible machanisms of stable information storage: experimental evidence. 7. Pssible mechanisms of stable information storage: theoretical formulations. 8. The statistical approach: (1) Hebb and contiguity. 9. Effects of contiguity. 10. The statistical approach: (2) Lashley and temporal patterns. 11. Brain potentials: some inter-relationships and behavioral correlates. 12. Representational systems. 13. Establishment of common response modes during conditioning. 14. The functional role of endogenous temporal patterns. 15. Wave shapes and information. 16. Conclusion.