Luca Salasnich Instability and Chaos in Spatially Homogeneous Field Theories (1296K, Latex with 4 PS figures) ABSTRACT. Spattially homogeneous field theories are studied in the framework of dynamical system theory. In particular we consider a model of inflationary cosmology and a Yang-Mills-Higgs system. We discuss also the role of quantum chaos and its application to field theories.