Wireless devices and their services are becoming increasingly important for many people’s lives. The services provided by these mobile devices enable users to work without space or time limitation. However, while these applications allow users to record and retrieve information about tasks and data, the relationships between tasks and data are left out. However, we have observed that many of people’s daily activities are not independent, and they are likely to be process-oriented. In this thesis, we develop a personal workflow model that is used to capture the requirements of personal processes. This model also includes a set of primitive operations that can be used to express queries on personal processes. The algebraic properties about these operations and how to optimize queries comprised of these operations are studied. Based on these operations, we propose an SQL-like query language to ease users’ query expressions. Besides, to actively remind the mobilers the right things to do at the right place and the right time, we propose a rule model that resembles event-condition-action (ECA) rules proposed for active database systems. All of the proposed features except for the rule model are implemented on Palm Pilot PDAs.