Systems analysis is defined as the use of scientific method with conscious regard for the complexity of the object of study. It has strong relationships with problem solving, in that the same four phases–lexical, parsing, modelling, and analysis–are identifiable in both. Examination of each of these phases reveals some of the problems involved in the use of systems methods in ecology. A model of a precipitation—evaporation system is presented as an example. Problems in experimenting with models of systems and with control, optimization, and comparison of such models are considered.