The present study deals with a typology of transcategorial processes such as nominalization and verbalization. In particular, it addresses the following question: What are the factors that determine the order in which the particular verbal categories are lost and nominal categories acquired in the transcategorial processes? It is argued that predictions concerning disruption/acquisition of categories in transcategorial processes are determined by semantically based hierarchies of nominal and verbal categories. That is, categories that are less relevant to the meaning of the stem are more ‘affected’ by transcategorial operations. The paper presents evidence from a sample of languages for this hypothesis demonstrating in turn the gradual disruption of verbal characteristics along the deverbalization cline and the gradual acquisition of nominal features along the substantivization cline. In the next sections I introduce a Generalized Scale Model for nominalizations, which obtains from the mapping of the two hierarchies onto each other, as well as discuss additional constraints on GSM due to the fact that some verbal and nominal categories are incompatible (‘blocking constraints’). The final part addresses the question whether Generalized Scale Model can be applied to other types of transcategorial processes, such as ‘verbalizations’. Throughout the paper special attention has been accorded to structural factors (such as morpheme order and category cumulation) that can interfere with the hierarchy constraints. More generally, this study aims to demonstrate how functional and structural factors conspire to constraint the outcome of transcategorial processes.