The volume contains the texts of four courses, given bythe authors at a summer school that sought to present thestate of the art in the growing field of topological methodsin the theory of o.d.e. (in finite and infinitedimension),and to provide a forum for discussion of the wide variety ofmathematical tools which are involved. The topics coveredrange from the extensions of the Lefschetz fixed point andthe fixed point index on ANR's, to the theory of parity ofone-parameter families of Fredholm operators, and from thetheory of coincidence degree for mappings on Banach spacesto homotopy methods for continuation principles.CONTENTS: P. Fitzpatrick: The parity as an invariant fordetecting bifurcation of the zeroes of one parameterfamilies of nonlinear Fredholm maps.- M. Martelli:Continuation principles and boundary value problems.- J.Mawhin: Topological degree and boundary value problems fornonlinear differential equations.- R.D. Nussbaum: The fixedpoint index and fixed point theorems.