  While there has been substantial empirical work identifying factors that
influence the contribution to, and use of open source software, we have as yet
little theory that identifies the key constructs and relationships that would
allow us to explain and predict how open source ecosystems function. What is
needed is a clearly articulated and empirically validated theory of open source
ecosystems. Such a theory should: $\bullet$ Explain why, how, and when key
resources---primarily the work of developers---are attracted to or depart from
a project or an ecosystem. $\bullet$ Explain why, how, and when projects and
ecosystems move through a life cycle, from initiation, growth, maturity, and
decline and death. $\bullet$ Explain how decisions about use are made, and how
the cumulatively influence the socio-technical position of a project within an
ecosystem, and the relations of ecosystems to each other.The remainder of this
chapter provides a sketch of such a theory in the form of a set of
propositions, which may form the foundation for future empirical work
