This dissertation studies the problem of safety communication in vehicular networks. Despite advances in automative safety during the past decades, still thousand of injuries and fatalities happen yearly in vehicle-related accidents. Dedicated Short Range Communication (DSRC) technology enables vehicles to communicate to each other through wireless medium, so they can inform each other of a potential danger on the road. Two important applications of vehicular network technology are collision avoidance and collecting traffic information. Collision avoidance relies on periodic sharing of safety messages to avoid accidents. Each vehicle that receives these safety messages from its neighbors, uses them to determine if any of the neighbors poses a collision threat. If a vehicle determines that this is the case, the onboard unit will warn the driver. For collision avoidance it is important that the status data of the vehicles be delivered on time and so the Medium Access Control (MAC) protocol design is very important. This dissertation studies two different approaches to the MAC design protocol: First, we use the QoS mechanism of IEEE 802.11 to reduce the collision rate among safety packets when IEEE 802.11p is used which is the likely scenario in United States. Then, we introduce a new contention-free TDMA-based MAC protocol tuned for vehicular communication which can guarantee an upper bound on the delivery delay of safety messages. Finally, we propose a strategy for collecting safety information of vehicles in a Road Side Units (RSU). This information can be used for analysis on the road traffic condition which can be then shared through a disseminating strategy with the vehicles on the road.