This collective volume focuses on the crucial role of formal evidence in recognizing and explaining instances of grammaticalization. It addresses the hitherto neglected issue of system-internal factors steering grammaticalization and also revisits formal recognition criteria such as Lehmann and Hopper s parameters of grammaticalization. The articles investigate developments of such phenomena as modal auxiliaries, attitudinal markers, V1-conditionals, nominalizers, and pronouns, using data from a wide range of languages and (in some cases) from diachronic corpora.