Youngsters aged between 10 and 15 were detected for 29,402 crimes and offences in 2011-12 – a drop of almost 11,000 on the total of 40,341 from 2009-10.
With 32,826 crimes and offences detected in 2010-11, the total for the last three years reached 102,569.
A crime or offence is regarded as being detected when there is enough evidence under Scots law to justify considering criminal proceedings.
But in Scotland children under the age of 12 cannot be prosecuted in the courts, and children aged between 12 and 15 are often dealt with though the children's hearing system.
The figures were released to the Conservatives after Freedom of Information requests were submitted to all eight of Scotland's police forces. They revealed 10 to 15-year-olds were detected for 295 cases of rape or other sexual offences in the last year alone.
Tory justice spokesman David McLetchie said: "What does it say about society that we've had tens of thousands of children running around the country committing serious crimes and carrying weapons?"
A Scottish Government spokesman said: "Recorded youth crime is falling sharply. Our whole system approach aims to nip early offending in the bud."