Electron beam induced deposition (EBID) has been investigated by many researchers for a number of applications requiring maskless deposition of material. Here, a scanning electron microscope is used to perform EBID of cobalt (Co) nanoparticles, which are then used as the catalyst for selected-area growth of carbon nanotubes (CNTs). Co nanoparticles were deposited using cobalt tricarbonyl nitrosyl as the precursor. They are oxygen plasma ashed to remove residual carbon from the deposition process prior to the growth of CNTs using a chemical vapor deposition (CVD) process. Co deposits made using different doses were found to have different catalytic properties. At sufficiently low doses, the deposits were insufficient to catalyze any CNT growth. At higher doses, single-walled CNT (SWCNT) growth was observed. Still higher doses produced deposits that catalyzed multiwalled CNT growth as well as some SWCNT growth. These differences in catalytic behavior are believed to result from nanoparticle size variations between and within the deposits. As a result, by using EBID deposited catalyst, it is possible to not only control where CNTs grow but also the kind of CNTs (SW or MW) grown during a single CVD run.