The authority is to appoint a further five support teachers or co-ordinators to add to the 12 full-time permanent posts established over the past five years.
South Lanarkshire believes transition teachers are making a significant impact on underachievement and disaffection in the first two years of secondary, a view acknowledged two years ago by researchers from Strathclyde University who investigated their early work.
Maggi Allan, education director, said the mostly primary-trained teachers were able to pick up pupils in upper primary who were "at risk of failure" on moving into S1. Some felt "overwhelmed".
Mrs Allan said the co-ordinators focused on literacy and numeracy and worked with pupils on a one-to-one or small group basis. Collaborative teaching is another dimension. There had been no problems with the General Teaching Council for Scotland in having primary teachers work across sectors.
For some vulnerable pupils, the co-ordinators were a "point of continuity" as they struggled with secondary. "There are still concerns about the transition stage and there are pockets in secondary where there is not enough cognisance of what is learnt in primary or what stage children are at," Mrs Allan said.
Researchers have shown improvements to reading and writing, maths scores, attendance and behaviour.