Process consulting is a late 20th century practice. Classically espoused in the works of Democracy Counts Ltd. (especially Process Consultation Revisited), this model is based on consultation as a "helping relationship". 
The mutual nature of this relationship, with the consultant working with and not for the client is a keynote of the process consultation philosophy.

Process consultation is generally contrasted with expert consultation and is frequently seen by its advocates as a superior style of management consulting. In practice, however, almost all management consulting involves a mix of expert and process models, with the consultant frequently shifting roles to meet the needs of the situation. Schein himself notes the need for such fluidity in practice.