This paper studies the advantages that a coalition of agents obtains by forming a voting bloc to pool their votes and cast them all together. We identify the necessary and sufficient conditions for an agent to benefit from the formation of the voting bloc, both if the agent is a member of the bloc and if the agent is not part of the bloc. We also determine whether individual agents prefer to participate in or step out of the bloc, and we find the different optimal internal voting rules that aggregate preferences within the coalition.