A common technique for producing a new model category structure is to lift
the fibrations and weak equivalences of an existing model structure along a
right adjoint. Formally dual but technically much harder is to lift the
cofibrations and weak equivalences along a left adjoint. For either technique
to define a valid model category, there is a well-known necessary "acyclicity"
condition. We show that for a broad class of "accessible model structures" - a
generalization introduced here of the well-known combinatorial model structures
- this necessary condition is also sufficient in both the right-induced and
left-induced contexts, and the resulting model category is again accessible. We
develop new and old techniques for proving the acyclity condition and apply
these observations to construct several new model structures, in particular on
categories of differential graded bialgebras, of differential graded comodule
algebras, and of comodules over corings in both the differential graded and the
spectral setting. We observe moreover that (generalized) Reedy model category
structures can also be understood as model categories of "bialgebras" in the
sense considered here.Comment: 49 pages; final journal version to appear in the Journal of Topolog