Young people are not yet getting access to a full range of academic, vocational and work-based learning courses, says inspection agency Estyn.
The Assembly government wants to broaden the learning choices of 14 to 19-year-olds, in a bid to reduce drop-out rates and raise qualification levels. It launched an action plan earlier this month (TES Cymru, April 7).
But Estyn says local networks set up in all 22 Welsh LEAs to deliver more courses have yet to get up to speed. Meanwhile, competition between schools and colleges for post-16 students is often deterring joint working.
Chief inspector Susan Lewis said: "Arrangements for delivering the 14-19 curriculum vary greatly. However, as yet, none of the new learning networks in Wales has the full range of options available for learners.
"A few networks have been very active in developing partnerships. But, because of competition for the recruitment of post-16 learners, there are often tensions between providers. These tensions can work against the efforts of the networks to build partnerships that offer wider choice."
Inspectors says current academic qualifications (A-levels and GCSEs) successfully meet the needs of pre-and post-16 learners.
But while providers are beginning to offer more vocational routes, there are too few vocational qualifications available at equivalent levels to GCSEs, nor enough in Welsh.
Meanwhile, many of the 14-19 networks are unaware that the lessons learned from piloting the Welsh baccalaureate apply to their work.
Both learning pathways and the bac offer a "core" programme of broader study, including key skills, work-based experience, community service, and other employability skills such as team-working and presentation.
Pupils in schools need to know about the range of choices available, and schools need guidance on local employers' needs so they can prepare learners for local jobs, says Estyn.
And the Assembly government should prioritise the linking of academic "credits" to the most popular academic and vocational courses, so learners can gain credit for partly-completed qualifications. An Assembly government spokesperson said: "We will consider Estyn's report carefully and take any action that is appropriate to improve the education of young people in Wales."
Meanwhile Cardiff, as part of its school reorganisation proposals (see below), is considering creating 11-14 and 14-19 campuses in the east and west of the city, to help to deliver learning pathways.
Hugh Knight, chief schools officer, said such arrangements, made in the east in collaboration with Glan Hafren college, would ensure "significant additional access to vocational education".
Citing the school and college collegium which already serves students in the south of the city, he added: "In Cardiff, we have practical examples of how it can work, by bringing providers together to offer a wider range of courses."
Dewi Jones, head of Glyn Derw high, Ely, which could be federated with nearby Michaelston community college with provision split between the two sites, was cautious.
"The 14-19 agenda is new to us all. We are trying to tackle it in our own ways. It's going to be a different way of delivering the curriculum and we have to adjust to it.
"But we have to work out what the implications of federation would be."