New research shows three-year-olds who are cared for by relatives have better language skills than those in crèches.
However, it is the only category where children in that setting fared better, research from Tusla shows.
The study, due to be published shortly, also found children in crèches had better motor skills by the age of three.
Tereasa Heeney from Early Childhood Ireland said the report also shows that factors other than childcare are more important to development.
"It also says development is clearly linked to the parents' educational levels, income, and employment status," she said.
"Middle-income parents - professional parents - are better-equipped to afford non-parental childcare than families on low incomes."