The main theorem shows that if M is an irreducible compact connected
orientable 3–manifold with non-empty boundary, then the classifying
space BDiff(M rel ∂M) of the space of diffeomorphisms of
M which restrict to the identity map on ∂M has the homotopy type
of a finite aspherical CW–complex. This answers, for this class
of manifolds, a question posed by M Kontsevich. The main theorem
follows from a more precise result, which asserts that for these manifolds
the mapping class group H(M rel ∂M) is built up as a
sequence of extensions of free abelian groups and subgroups of finite
index in relative mapping class groups of compact connected surfaces.