Inspectors awarded it the complete set of "very good" scores for all 11 quality indicators that are used to judge the performance of education authorities; nothing was found to be merely good, fair or unsatisfactory.
The top accolade was even extended to the achievement of continuous improvement in its schools, which had only been awarded to Inverclyde until now and eluded the previously top-performing authorities of Stirling and South Lanarkshire.
The council's performance was judged so remarkable that Peter Peacock, Education Minister, took the unprecedented step of writing to commend it.
Mr Peacock now wants the authority to tell "the widest possible audience" how it can be done.
The "hands-on" leadership of John Wilson, East Renfrewshire's director of education, was described as "outstanding" - which is presumably, in HMI terms, on a par with the "inspirational" leadership of Maggi Allan, his South Lanarkshire counterpart. "Outstanding" was used in the latter's HMI report as well, but it was applied in a collective sense.
The council's schools regularly top or come second in the exam pecking order but, inspectors found, it is not resting on its laurels and "was working to achieve further improvements in aspects of the curriculum and in the quality of learning and teaching.
"Very importantly, schools in economically disadvantaged areas were closing the gap in some aspects of attainment with those in more affluent areas, and the performance of several groups of lower attaining learners had improved."
HMI's judgment of a very good performance in continuous improvement was partly derived from a remarkable 96 per cent of headteachers who told inspectors they were confident that the council's education department helped them improve the quality of what they were doing.
The authority's policy of "support and challenge" had led to "impressive levels of attainment" in high-performing schools which continued to improve - and to a narrowing of the gap between them and schools in areas of deprivation. Despite very positive initial inspections of schools, follow-up action was "reassuringly rigorous and challenging".
The inspectorate even found the council had been able to forge improvements in the "problem" years of S1-S2, with performance in reading, writing and maths in S2 above or well above national averages and the record of similar councils, over the period 2001-04.
The tracking of pupil progress and school improvement is partly made possible by the "highly effective (and) excellent" management information unit known as EMIS, which collates and analyses pupil and school performance - even down to the level of individual classes.
While East Renfrewshire is seen as "relatively affluent", and therefore with many advantaged schools, the report points out that the poverty index of free school meal entitlement in secondary schools (9.4 per cent) is actually above that for authorities in similar circumstances and only slightly below in primary schools. The authority also has "one of the most ethnically diverse populations in Scotland" .
With the publication of two HMI reports this week, that leaves only Orkney (whose report is due next Tuesday) and Argyll and Bute as the final councils among the 32 in this first round of inspections.