As artificial materials become more integrated with biological environments, the demand for finely-tuned surface modifications will increase. More specifically, the surface immobilization of multiple functionalities in defined ratios would be of high value for applications such as biological assays, micro-total analytical systems (μTAS), and biomedical devices. The ability to mix and match surface functionalities which possess contrasting properties would allow one to screen for trends in cellular interactions. This talk will focus on chemical vapor deposition (CVD) copolymerization as a novel method of depositing copolymer coatings with multiple reactivities. Complex substrate geometries do not hinder the CVD process, making it a flexible method for room-temperature surface modification. We utilize a modified Ghoram process to deposit functionalized parylene (poly(p-xylylene)) copolymers from their analogous [2.2]paracyclophane derivatives. Two differently-functionalized [2.2]paracyclophanes are copolymerized and deposited. These functionalities are presented at the polymer surface in specific ratios, simply by modifying the CVD process conditions. FTIR spectroscopy and XPS of various poly(p-xylylene) copolymers verify that the functional groups are maintained while avoiding in situ cross-reaction. Furthermore, these copolymers are reactive and can immobilize two biomolecules in specific ratios. We also demonstrate preliminary biocompatibility of poly(p-xylylene) homo- and copolymers. Immobilization of two anti-thrombotic biomolecules onto the same substrate was achieved. Also, we use CVD polymerization to fabricate coatings which possess reactive surface composition gradients. These surfaces are capable of further immobilizing two biomolecules as gradients.