The unpublished report, which has been seen by The TES Scotland, was compiled by Philip Banks, a retired chief inspector of education, who was commissioned by the Scottish Executive to examine the support required for boards to function more effectively.
The report discloses major criticisms of the way boards are forced to operate and scepticism of how representative of parents they can be with a maximum of only 10 members. It takes a tentative view of whether boards and parent teacher associations should merge, a controversial step which could combine the Scottish School Board Association and the Scottish Parent Teacher Council.
Mr Banks states: "More could be done to publicise and explain the work of school boards as part of a relaunch of the movement within the context of new policies for inclusiveness and recent education legislation. Aspects of school board arrangements could be made more palatable and less threatening for parents who may otherwise be willing to serve on school boards.
"A closer link between school board activities and the more accessible PTA activities may widen the parent base. Without doubt, increasing parental involvement is the biggest challenge facing school boards and will require a long-term sustained strategy."
The report says boards are having difficulty recruiting, particularly from disadvantaged and minority communities. One reason could be that administrative and electoral procedures are "bureaucratic, legalistic and daunting".
But even where parents are attracted to serve, the report has reservations about how representative they are. This is underlined by the fact that the six authorities consulted by Mr Banks have virtually all set up consultative machinery with parents to supplement the school board network.
One director of education is quoted as saying that boards are so unreliable at conveying parent views as to be "largely irrelevant" for the purposes of consultation.
Mr Banks found that boards are still suffering from the political legacy of their establishment, when they were regarded as a vehicle for encouraging schools to opt out of local authority control. The report notes drily: "This point of embarkation is not the most promising for the creation of constructive symbiosis between schools and school boards."
This unpromising birth has led "a significant proportion of headteachers" to retain a lingering suspicion that boards are there to be "handled" or even "manipulated" for the good of the school.
Mr Banks also calls for improvements to the "haphazard" training offered to parents and teachers serving on boards, and action on the highly variable funding of boards, the swamping of boards with "routine and blanket circulations" and the quality of support from education authorities.
On a merger of the SSBA and the SPTC, the report warns that the current strengths of the separate organisations "should not be compromised by a cosmetic rearrangement that looks tidy but results in a diffused sense of purpose".