Refection Positivity is a central theme at the crossroads of Lie group representations, euclidean and abstract harmonic analysis, constructive quantum field theory, and stochastic processes.

Preface.- Introduction.- Reflection positive Hilbert spaces.- Reflection positive Hilbert spaces.- Reflection positive subspaces as graphs.- The Markov condition.- Reflection positive kernels and distributions.- Reflection positivity in Riemannian geometry.- Selfadjoint extensions and reflection positivity.- Reflection positive representations.- The OS transform of linear operators.- Symmetric Lie groups and semigroups.- Reflection positive representations.- Reflection positive functions.- Reflection positivity on the real line.- Reflection positive functions on intervals.- Reflection positive one-parameter groups.- Reflection positive operator-valued functions.- A connection to Lax-Phillips scattering theory.- Reflection positivity on the circle.- Positive definite functions satisfying KMS conditions.- Reflection positive functions and KMS conditions.- Realization by resolvents of the Laplacian.- Integration of Lie algebra representations.- A geometric version of Fr¿ohlich's Selfadjointness Theorem.- Integrability for reproducing kernel spaces.- Representations on spaces of distributions.- Reflection positive distributions and representations.- Reflection positive distribution vectors.- Distribution vectors.- Reflection positive distribution vectors.- Spherical representation of the Lorentz group.- Generalized free fields.- Lorentz invariant measures on the light cone and their relatives.- From the Poincar¿e group to the euclidean group.- The conformally invariant case.- Reflection positivity and stochastic processes.- Reflection positive group actions on measure spaces.- Stochastic processes indexed by Lie groups.- Associated positive semigroup structures and reconstruction.- A Background material.- A.1 Positive definite kernels.- A.2 Integral representations.- Index.