This year's festival is the 24th in Edinburgh and the 16th in Glasgow and opens in both cities with a concert by the JeugdOrkest Nederland which features a contemporary work by Tristan Keuris, Schumann's Cello Concerto and Shostakovich's formidable Symphony No 5. That is a demanding programme for any orchestra and is typical of the ambition which runs through the programme.
Carol Main, the director of the festival, says there seems to be more big symphonies than usual in the programme this year, but is not surprised to see the high level of effort.
"Success often is down to picking the right repertoire for the group," she says, "but that does not mean they avoid challenges. Far from it.
"This is not a programmed festival in the usual sense; we don't have an input into those choices. To some extent we have to take it as it comes, but I find it remarkable that we achieve such a consistent high standard on that basis."
Hard work invariably lies behind that achievement, often against the conflicting pull of school work and other leisure activities on the time and commitment of the players and their tutors. Every school or region will prepare in their own way but Graeme Wilson, the education adviser for Fife, has insight of how they go about preparing the youth ensembles they send to the festival.
Each year, Fife sends its youth orchestra, concert band, string orchestra, percussion ensemble and the Kingdom Fiddlers. "The groups will have been working toward concerts in Fife earlier in the year," Mr Wilson explains, "so the festival is an enhanced opportunity to go on to a larger stage.
"I've done the festival for quite a few years with the kids but I'm always amazed by how excited they are at getting the opportunity to go and perform on another platform.
"They meet spasmodically as far as rehearsals are concerned. We can't get them to commit to regular meetings over the winter. The youth orchestra starts in October, and we hold a residential week at Loaningdale House in Biggar, which is the core of their work. We then get together again in February and add some more music.
"From then there is literally nothing until we meet for another weekend at Biggar in August to prepare the festival programme. I'm amazed how quickly they can pull it all back together, although that is down to the hard work they have done earlier in the year.
"We have used the facilities at Biggar for many years and I have persisted with that because I believe that the opportunity for both residential work and sustained hours of work really plays off. Rather than have them do a couple of hours of work, then go away and forget everything they have done, we are able to take them into a lovely environment and work with them intensively for four or five days.
"All four bands go down there at different points in the year. It's a lot of work administratively, but well worth the effort."
Groups from Edinburgh, Glasgow, East Dunbartonshire, the west of Scotland, Perth, Midlothian and the Scottish Borders, as well as Fife, will be represented at the festival this year. One new group will be a string ensemble from St Mary's Music School, the acclaimed specialist school in Edinburgh. St Mary's has recently joined the National Association of Youth Orchestras, under whose auspices the festival is run.
The Scots will be complemented as usual by a contingent of orchestras from England, a jazz orchestra from Sweden and the Haydn Youth String Orchestra of the Netherlands, as well as the crack Dutch orchestra already mentioned.
Festival of British Youth Orchestras, August 9-31 www.nayo.org.ukTickets and information from the Edinburgh Festival Fringe box office, tel 0131 226 0000, and the Royal Scottish Academy of Music and Drama, Glasgow, tel 0141 332 5057