This lecture in Biochemistry addressees denaturation and the folding problem.  Some of the means to denature a protein are mentioned, including temperature, pH, hydrophobic solvents, detergents and chaotropic reagents (urea and the guanidinium ion). How proteins (which are synthesized like beads on a string) fold to functional tertiary structures are examined with particular attention spent on ribonuclease A..  The steps and energetics of the folding process are discussed.