This paper sheds new light on the economic logic of voluntary associations and the relationship between individual contribution and collective action. The aims are twofold. Firstly, we seek to explain how "team reasoning" (Bacharach et al. 2006) can deeply change the functioning of voluntary associations (which are considered to produce a public good) when some or all of the individual members group together to make collective decisions about their involvement or contribution, rather than deciding separately. Secondly, we seek to better understand the effects of heterogeneity of resources on individual involvement, in terms of both the budget constraints of individual members and their capacity to contribute differentiated non-monetary contributions to the association, in relation to the diversity of their personal abilities and preferences about the characteristics of the good produced. To this end, we use a model of voluntary association collectively producing a public good, where monetary contributions (compulsory fees plus voluntary donations) is combined with volunteering. We analyze the conditions for an association to offer profitable conditions to its members and the consequences that can be drawn in terms of its existence and size. We show that, at equilibrium, the level of voluntary contributions is ceteris paribus higher when individuals make their decisions on the basis of team-reasoning rather than individually. We analyze the role played by heterogeneity of incomes in the formation of teams within associations. We then introduce the concept of subjective quality into the basic model. The originality of the model is that we assume the public good to be characterized by at least two main components: quantity and quality. The quantity is considered here as a purely public component, insofar as all the members benefit equally from it. However, the quality of the public good is assumed to be a mixed (public and private) component. The agents can enjoy part of it in the same way, but there may be certain characteristics of quality that are difficult or impossible to measure objectively. Quality is always somewhat subjective, to the extent that perfect correspondence with the preferences of heterogeneous agents is unlikely to occur. In our model, the agents can contribute money and/or time and effort. The latter, which we call volunteering, allows them to influence the quality of the good (or service) provided according to their own preferences.