The determinants and consequences of teachers' beliefsResearchers in the social cognition field have suggested that t e a ch e rs' beliefs about, and attitudes towa rd, student diversity and heterogeneity play a central role in students' i n t egration into standard settings (Semmel, Abern at hy, Butera & Lesar, 1991). In part i c u l a r, empirical data show that teach e rs possess low academic expectations in relation to children with special educational needs. In a study by Aloia, Maxwe l l and Aloia (1981), teachers' impressions of the intellectual potential of a child who was labelled as 'mentally retarded' were lower than those for a non-disabled child.What is more, early studies on educational integration (for example, Jamieson, 1984) found that teachers were very apprehensive about the quality of the academic work that children with special educational needs would produce once they were integrated in regular classrooms. They also expressed other doubts, namely concerns about the degree to which children were prepared for integration and the amount of individualised education time that would be required by pupils with special learning needs (Bender, Vail & Scott, 1995).Despite the ge n e ral acceptance of the principle of integration, some studies reveal that teachers do not seem ready for it (Semmel et al., 1991). This scenario is also supported in Scruggs and Mastropieri's (1996) review of studies conducted between 1956 and 1995, wh i ch concluded that about 70% of teachers support the concept of mainstreaming, but that only a third feel that they have sufficient time, skills, training or resources to support the practice of integration.In overall terms, teachers' attitudes toward integration are determined by several factors. The first of these is training. Bender et al. (1995) showed that teachers' attitudes toward school integration did positively correlate with the number of in-service training courses on teaching children with special educational needs that they had taken. According to these data, teach e rs wo rking at higher gra d e -l eve l s displayed more negative attitudes. Experience is a second factor. Data from a study by Center and Ward (1987) showed that younger teachers -and consequently those with less teaching experience -displayed more favourable attitudes toward mainstreaming. Chalmers (1991) showed that elementary and secondary teachers tend to differ in both their views of integration and the kinds of classroom accommodations they make for students who experience special educational needs. Villa, Thousand, Meyers and Nevin's (1996) research on the perceptions of teachers and a d m i n i s t rat o rs wo rking in heterogeneous educat i o n environments suggest that experience with the practice of i n cl u s ive education develops teach e rs' ab i l i t y, their perception of competence and their belief in educating heterogeneous classes. What is more, findings from a study by Soodak, Podell and Lehman (1998) indicate that teachers who possessed low teaching efficacy; who lacked...