Pupils learning Gaelic "match and better" their peers in other subjects, Highland Council has said.
This year's exam and attainment results for Gaelic-medium pupils demonstrated the clear benefits of bilingual education, said the council. Hamish Fraser, chair of its Gaelic committee, said: "Far from holding pupils back, as some critics would have it, this is proof again that pupils learning in Gaelic-medium schools not only do well in Gaelic but match and better their peers in other subjects."
Education director Hugh Fraser said some of the Gaelic-medium pupils came from families where it was not spoken but, nevertheless, showed a good standard of written and spoken Gaelic. "Another key result is that the Gaelic-medium pupils do better in English than their `mainstream' counterparts. This helps to demonstrate the fundamental benefit of receiving a bilingual education," he said.
Mr Fraser told the Gaelic committee that by the end of S2, the average percentage of pupils achieving level E in Gaelic over the past five years had been 72.6 per cent in reading and 58 per cent in writing.
The equivalent reading and writing in English scores for these pupils were 79.7 per cent and 68.2 per cent respectively - around 9 per cent higher than the average for the year groups as a whole.
Gaelic-medium pupils also gave a good performance in mathematics. By the end of S2, the average percentage of Gaelic-medium pupils over the past five years was 74.2 per cent - around 8 per cent higher than the average of the year groups as whole.
Almost all Gaelic-medium pupils continued to the end of S4 where they sat exams specially designed for native speakers, he added. Again, achievement levels were good, with a higher proportion gaining Standard grade Credit level awards than the overall cohort in English. Pupils learning Gaelic as a curriculum subject also did well: at Credit level, they surpassed pupils doing French and German by around 10 per cent; at General level, they were only slightly behind.