The unlicensed frequency band around 60 GHz is a very promising spectrum due to its potential to provide multiple gigabits per second based data rates for short range wireless communication. Hence, 60 GHz radio is an attractive candidate to enable ultra high rate Wireless Personal Area Networks (WPANs), which are expected to support wireless multimedia applications like high-definition video streaming, ultra high speed content download, etc. Till now, the main research effort related to 60 GHz radio is at the physical layer design and channel model investigation. However, the unique properties of 60 GHz radio also create new research challenges for 60 GHz networking. Hence the aim of this dissertation is to provide an in-depth view on the Medium Access Control (MAC) layer and Network layer design for 60 GHz WPANs. To obtain sufficient link budget for multiple gigabits per second based wireless communication, directional antennas are needed in 60 GHz systems. Although directional antennas exhibit many advantages compared to omni-directional antennas, their deployment is very challenging for the MAC and Network layer protocols. For instance, to set-up directional connections, devices are expected to know the direction of their neighbors. The performance of directional neighbor discovery protocols is investigated in this dissertation to review the impact of directional antennas on the network setup durations. With the knowledge of orientation information of the network components, a resource management scheme, especially for the IEEE 802.15.3 featured WPANs, is proposed to support concurrent transmissions using directional antennas in a Time Division Multiple Access (TDMA) fashion with Quality of Service (QoS) and fairness provisioning. To further improve the transmission efficiency of the MAC layer protocol, standard frame aggregation and low latency frame aggregation mechanisms are investigated to alleviate the impact of transmission overhead. Another issue addressed at the MAC layer in this dissertation is how to support highly-reliable transmissions using 60 GHz radio. Due to the weak penetration and reflection properties, the Line-of-Sight (LOS) link between two 60 GHz components is easily blocked by obstacles in indoor environments, which is a severe hurdle that influences the reliability of 60 GHz systems. To resolve the link blockage problem, instant decision based beam switching mechanisms and environment learning based beam switching mechanisms are proposed in this dissertation targeting for different usage scenarios. Furthermore, to support the coexistence of multiple 60 GHz WPANs, a systematic analysis of using synchronization frame to mitigate Co-Channel Interference (CCI) is performed. It has been shown that the link capacity and the guaranteed transmission distance within a WPAN are upper bounded by the CCI. To enable the multi-hop communication among these inter-connected 60 GHz WPANs, the Network layer design is involved in this dissertation. First, a fundamental investigation is provided in ad-hoc networks for using directional antennas in the aspects of topology control and message dissemination. The results provide valuable insights for using directional antennas for multi-hop communication. Second, focusing on the specific network topology of WPANs, the performance of inter-piconet route discovery is examined. Moreover, a joint QoS routing and channel resource allocation mechanism is proposed to resolve the inter-piconet channel resource reservation collision problem.