Abstract: This dissertation, in broad terms, focuses on the theoretical analysis of the mechanisms of human interaction in the context of sequential decision-making under imperfect information. The first chapter analyzes a sequential decision model with one-sided commitment in which decision makers are allowed to choose the time of acting (exercising a risky investment option A) or waiting. The existing literature assumes an exogenous ordering of decision makers, in which only one decision maker moves in each period in an exogenously given order. If information previously aggregated dominates their own private information, individuals ignore their own private information and follow their predecessors—herding occurs. Consequently, their decisions are uninformative to others, which prevents information aggregation. Therefore, initial realization of signals can have long-term consequences and herd behavior is often error prone. My main question of inquiry is: if we allow decision makers to choose the time of acting or waiting, will herd behavior be more or less error prone? I characterize herd behavior under endogenous ordering and show that with endogenous ordering, if the number of decision makers is large and decision makers are patient enough, at any fixed time, nearly all decision makers wait due to the negligible information disclosed. In this case, if decision makers can be forced to move with an exogenous order, the resulting equilibrium is more efficient because exogenous ordering tends to aggregate more information. The second chapter investigates the two-sided commitment case, in which decision makers have the third choice, exercising a safe investment option B. Results obtained in this case are similar to those found in the one-sided commitment case. However, one striking result is that with endogenous ordering and two-sided commitment, even though waiting forever is a dominated strategy, if the number of decision makers is large and decision makers are patient enough, decision makers wait too long. The third chapter explores what group reputation is and models its formation and evolution. I define a player's group reputation as the belief others have about the characteristics of the group he belongs to, which is based only on group signals. A player's individual reputation is derived from his group reputation by adding individual signals. A model of group reputation of civil servants is constructed to identify the strategic behavior of potential bribers and civil servants, the corresponding levels of corruption, and possible anti-corruption policies along with their effects.