One of the most interesting and fundamental areas of economic analysis concerns the provision of public goods. As a generic term, a "public good" is one which is provided and financed by many people, but can be used by individuals. Obvious examples are goods and services provided by governments to citizens in general. On a smaller scale the term can be applied to any situation in which a group, by acting in a collective fashion, can provide goods and services that the individual members of the group could not finance themselves. The pricing of public goods, that is to say the charges levied on the individual members of the group, is very important. A difficult problem is to invoke a pricing policy in which each user of the good pays a fair share of the cost of providing that good. Often, because of asymmetric information about usage, some members of the group pay more than their share while other members "ride free". The project explores two new research areas and expands our knowledge of public goods provision within the context of a voluntary contribution mechanism. The first topic examines a "nested" public goods problem in which groups may communicate only if they pay the organization costs associated with communication. The second area involves an experimental inquiry into the properties of public goods provision in large groups. Past work has shown that group size, particularly when endogenously determined, can significantly affect the outcome of public goods experiments. The project is done in collaboration with Mark Isaac of the University of Arizona. %%% One of the most interesting and fundamental areas of economic analysis concerns the provision of public goods. As a generic term, a "public good" is one which is provided and financed by many people, but can be used by individuals. Obvious examples are goods and services provided by governments to citizens in general. On a smaller scale the term can be applied to any situation in which a group, by acting in a collective fashion, can provide goods and services that the individual members of the group could not finance themselves. The pricing of public goods, that is to say the charges levied on the individual members of the group, is very important. A difficult problem is to invoke a pricing policy in which each user of the good pays a fair share of the cost of providing that good. Often, because of asymmetric information about usage, some members of the group pay more than their share while other members "ride free". This project applies the framework of experimental economics in two main areas of public good provision to assess the impact of information sharing among group members. In the first part communication costs are borne fully by the members. The second part of the work studies the affect of group size on the outcome of public good pricing.