The computing and networking capabilities of today's wireless mobile devices allow for seamlessly-networked, ubiquitous services, which may be dynamically composed at run-time to accomplish complex tasks. This vision, however, remains challenged by the inherent mobility of such devices, which makes services highly volatile. These issues call for a service-oriented middleware that should (i) deal with the run-time growth of the application in terms of involved services (flexibility), (ii) accommodate heterogeneous and unforeseen services into the running application (genericity), and (iii) discover new services at run time and rearrange the application accordingly (dynamism). This chapter discusses the design and implementation of ubiREST, a service-oriented middleware that leverages REST principles to effectively enable the ubiquitous networking of Services. ubiREST specifically defines a layered communication middleware supporting RESTful Services while exploiting nowadays ubiquitous connectivity.