The paper analyzes the birth process of small and medium manufacturing firms in Tuscany, an Italian region. In particular it explores, through a spatial microeconometric approach, the possible determinants of the location decisions of the new firms. The geographical distribution of the manufacturing firms born in Tuscany between the 2005 and the 2008 is defined in terms of a inhomogeneous marked point process in the continuous space and we evaluate the effect of space-varying factors, both exogenous and endogenous, on the location decisions of new firms by parametrically modeling the intensity of the process. Results show that the choice is influenced on the one hand by the availability of infrastructures and the level of accessibility, and on the other by the presence and characteristics of existing firms.