Radiation curable ink jet printing is rapidly developing new technology for digital imaging. The strict property requirements of an ink jet ink formulation in terms of viscosity, cure speed, cured film performance, pigment wetting and friendly EH&S profile present many challenges to the ink formulator and the supplier of radiation curable raw materials. Traditionally radiation cured inks and coatings have used relatively high molecular weight/high viscosity oligomers to acheive properties. The presentation will cover properties and performance aspects of monomers and oligomers suitable for radiation curable ink jet systems. A main focus will be on a new family of low-viscosity/high functionality polyester acrylates that address many of the performance issues noted above.