Inthis thesis single-molecule fluorescence resonance energy transfer(FRET)spectroscopy was used to study the folding of a protein that belongsto the large and important family of repeat proteins. Cohen showsthat the dynamics of the expanded conformations is likely to be veryfast, suggesting a spring-like motion of the whole chain. Thefindings shed new lighton the elasticity of structure in repeat proteins, which is relatedto their function in binding multiple and disparate partners. Thisconcise research summary provides useful insights for studentsbeginning a PhD in this or a related area, and researchers enteringthis field.