In her first annual report, Susan Lewis said that for all pupils the proportion of work judged satisfactory or better by the inspectors has risen by about 10 percentage points since 1993 and the share of work judged to be good has risen from a quarter to more than a third.
But weaknesses in literacy and numeracy and high truancy levels remain significant problems in Wales.
In all, standards of achievement were satisfactory or better in 90 per cent of the classes inspected last year, including 40 per cent where they were good. This puts Welsh schools within hailing distance of reaching the Government's target: that by 2002 more than 95 per cent of classes in Wales should have at least satisfactory results, with more than half either good or very good.
But standards of literacy are unsatisfactory in 15 per cent of primary classes and standards of numeracy unsatisfactory in 10 per cent. In these classes, pupils lack important knowledge and skills and are "unable to read independently, write effectively or use number flexibly to solve problems," the report says.
Marked improvements in the top primary years have not been matched by improvements in the middle primary years, where there tends to be a dip in achievement. The teaching in one in five classes at key stage 2 is judged unsatisfactory.
Welsh secondary schools score slightly better than primaries on quality of teaching, with half of the lessons seen judged to be good. But they face a serious battle against truancy.
"In almost half of the secondary and special schools inspected this year, poor attendance was a problem and often quite a serious one, especially in years 10 and 11," Ms Lewis says.
The report stresses the importance of good leadership and calls for more and better management training for school heads and deputies and heads of department.
The Annual Report of Her Majesty's Chief Inspector of Schools in Wales 1996-97 is available from HMSO bookshops, pound;18.