The HM Inspectorate of Education report, called Improving Scottish Education, lists the overall quality of youth work and achievements of young people among the main strengths of the community learning and development sector.
But it says there is not enough data on the outcomes of youth work to identify trends in achievement, and that improvements are needed to enable young people to see what they are learning and build on it.
Inspectors also call for developments in the Scottish qualifications framework to enable the achievements of young people on awards schemes to be recognised within national qualification frameworks.
Inspections of youth services between 2002 and 2005 show learning opportunities as "fair" in one in four authorities, "good" in about a third and "very good" in the remainder.
YouthLink Scotland's chief executive Jim Sweeney welcomed the news: "We're very keen to discuss new ways of improving the effectiveness of evaluation and assessment. We have to find more innovative ways of working."
