The focus of the study of teaching has shifted gradually away from the process-product research paradigm to one which emphasizes the role of teacher and student thought processes. Researchers have identified teacher planning as an area of study likely provide insights into the role of teacher thought processes. Since the 1970s a number of important studies into teacher planning have been completed. An examination of the teacher planning literature revealed that certain types and functions of planning recur in the research. The literature also shows that the rational-linear planning models which are prevalent in teacher pre- service education do not adequately describe teacher planning in practice. Several studies have attempted to describe teacher planning in terms of models. Although these studies more closely described actual teacher planning, modelling of teacher planning is incomplete. Some research has also attempted to establish relationships between teacher planning and teacher actions and the subsequent outcomes for students. Western Australian schools are presently subject to a climate of change driven principally by economic considerations. A fundamental shift in emphasis has occurred in teacher accountability policy and as a result teachers are now accountable for the outcomes of students instead of the traditional accountability for planning programmes of work. Case study techniques were used to examine the extent to which these policy changes and the associated de- regulation have affected the planning practices of six teachers. The thought processes involved in planning were described and a naturalistic model of planning was developed. The study found that the teachers did not plan as they 'should' in two respects. First, they only applied rational models when using planning formats which assisted them with the writing of objectives. In this respect the teachers did not apply the rational models from their pre-service education. Second, the teachers did not apply an outcomes approach to planning, as required by the Education Department accountability policy. The study also examined the six teachers' perceptions of accountability and the accountability techniques applied in two schools. The teachers perceived accountability as a professional obligation. Teachers were not being held accountable for planning within the school management information system. Although the focus for accountability discussions had shifted to accountability for student outcomes, the teachers continued to apply an activities- first approach to planning.