Software mobile agents is a new distributed computing paradigm which was developed to support efficient computing over the Internet. Since its inception there has been a significant research effort to produce concrete agent-based artefacts. This phenomenon resulted in the proliferation of a large number of agent systems, mostly based on proprietary programming languages, each with its own characteristics, peculiarities and assumptions. Hence the agent technology has largely remained hidden and incomprehensible by Internet end users. Moreover the issue of interoperability and integration of agents with existing legacy software has only just started to be addressed by the agent research community in a rather ad hoc way. In this thesis we attempt to design an agent architecture which is independent of any programming language and therefore is directly suitable for Internet end users. The proposed architecture, labelled as Mobile Agent System for Internet Computing (MASIC), addresses several important contemporary issues in agent research. It defines an agent as a container of reusable components that can be copied or moved to other agents. Each agent has a symmetric I/O access control module and is also equipped with associative access collaboration facilities. Additionally every agent contains a navigator module which stores the agent's itinerary plan and provides an interface via which the agent itself or other authorised agents can dynamically adapt the plan to reflect run-time events and constraints. The agent system provides an integrated access control architecture which enables an agent to define customised access control structures that can be fully or partially shared with other agents. Existing access control structures can be combined to create new structures that represent more complex access mechanisms. Agents can discover other agents offering pertinent services via an adaptive, customisable agent discovery architecture incorporated in MASIC. This discovery architecture enables the full interaction of links with queries and supports the definition of access paths which are tightly coupled with access control and. other customised services. MASIC also provides the conceptual architecture of a message-oriented agent communication system integrated with a mobility management scheme. Finally, this thesis presents the design and implementation of a prototype graphical interface which enables the potential user of the system to create, manage and interact with agents in real time. In conclusion the research presented in this thesis aims to provide a comprehensive, language-neutral, secure, collaborative environment within which mobile agents can interact with their peers in order to perform their tasks efficiently while human operators can oversee and manage these activities through a user friendly interface. The architecture is generic in nature as it can support general-purpose, agent-based computations. Its concepts, entities and mechanisms can be fully or partially re-used to provide architectural solutions to challenges in various application domains such as Knowledge Management, the GRID and E-Commerce.