In the first chapter, I examine in a controlled, experimental laboratory setting, the acceptance of a secondary currency when a primary currency already circulates in an economy. The underlying model is an indivisible good / indivisible money, dual currency search model similar to that in Kiyotaki and Wright (1993) and Craig and Waller (2000). In such models, there are two pure Nash equilibria - total acceptance or total rejection of the secondary currency - and one unstable, mixed equilibrium denoted as partial acceptance. This mixed equilibrium is considered an artifact of the indivisibility of money and goods in the model and is often ignored. I find that when barter between good holders is allowed, the equilibrium tends towards tota...