A ban on children sitting three to a seat on school buses has now been enforced by most local authorities, according to Assembly government officials.
But it is still unclear who has ultimate authority for transport safety outside the school gates - schools, bus firms or councils.
A progress report reveals how far local authorities have got in their attempts to make pupils belt up and sit two to a seat, as per the recommendations of a cross-party committee of Assembly members.
The proposals followed a campaign by the parents of a 12-year-old boy who died on his way home from Cowbridge comprehensive school in December 2002.
Stuart Cunningham-Jones, from the Vale of Glamorgan, was on the top deck of a school bus when it crashed. After the accident his parents called for all pupils to wear seat belts and for old double-decker buses to be scrapped.
The Assembly's education committee made 30 recommendations last May to improve safety. Officials told AMs last week that only a handful of Wales's 22 local authorities had opted to keep three pupils to a seat.
Elizabeth Taylor, head of the Assembly government's schools management division, said those that had not were "nervous" about leaving children stranded at bus stops if vehicles were full.
She also said bus drivers were now stricter in ensuring pupils on specified routes had a bus pass. However, she said progress had been slower elsewhere.
One recommendation was for the Assembly government was to clarify who is responsible for school bus safety.
This has not yet been achieved, according to the report, and the government has yet to issue guidance on drawing up codes of conduct for improving pupil behaviour on buses - another recommendation.
Consultation on the new guidance is expected to begin next month after talks with LEAs, bus operators, the Association of Transport Co-ordinating Officers, the Confederation of Passenger Transport and the Welsh Local Government Association.
The report said a review of safety within the school gates will also be undertaken by independent consultants this spring. The Health and Safety Executive is also to look into safety inside schools - including the management of vehicles and bicycles.
The Assembly government is providing an extra pound;1 million during the 2007-08 financial year to allow councils to improve school bus safety. But a WLGA report last summer claimed unruly pupils were still putting lives at risk on school buses, while the cost of improving safety could rocket to Pounds 20m.
Jane Davidson, education, lifelong learning and skills minister, welcomed moves by councils to bring in changes, including installing CCTV on buses.
However, she said that more needed to be done to phase out double-decker buses, make more use of security cameras and draw up codes of conduct to tackle pupil behaviour.
A high-profile meeting will take place between the minister and the WLGA later this month.