Freedom is a phenomenon in the natural world. This phenomenon - and indirectly the question of free will - is explored using a variety of systems-theoretic ideas. It is argued that freedom can emerge only in systems that are partially detennined and partially random, and that freedom is a matter of degree. The paper considers types of freedom and their conditions of possibility in simple living systems and in complex living systems that have modeling (cognitive) subsystems. In simple living systems, types of freedom include independence from fixed materiality, internal rather than external detennination, activeness that is unblocked and holistic, and the capacity to choose or alter environmental constraint. In complex living systems, there...