This chapter will present a research synthesis of a series of studies, termed here the Ealing research. The studies use the same general framework to conceptualise tasks and task performance, enabling easier comparability. The different studies, although each is self-contained, build into a wider picture of task performance. The major point of this research synthesis is to search for more powerful generalisations than are possible with separate individual studies. The generalisations concern the conditions under which tasks are done (particularly planning and post-task activities), and the influence of task characteristics, such as task structure, information organisation, and necessary elements. The findings then frame a discussion of two current theoretical accounts of tasks and task performance--the Trade-off Hypothesis and the Cognition Hypothesis, and it is argued that a more precise version of the Trade-off Hypothesis provides a better account of existing results. (Contains 9 tables and 4 footnotes.) [For complete volume, see ED539539.]