Campaigners have called for an end to "overcrowding" in foster care homes in Scotland.
There are concerns about pressure on children and carers
The Fostering Network has urged the Scottish Executive to limit the number of children put into homes to three, in line with the rest of the UK.
Unlike elsewhere, there is currently no limit to the number of children placed in foster homes.
The Scottish Executive said it had no immediate plans to restrict numbers but would keep the issue under review.
To mark the start of this year's Foster Care Fortnight on Monday, the Fostering Network has called on the executive to introduce a limit on the number of foster children per household.
It has concerns about excessive pressure on carers and disruption to children's lives.
The Fostering Network said statistics showed that there were 2,600 carers in Scotland caring for an estimated 3,500 foster children on any given day.
One in every four of these children lives with a family which already cares for four or more children.
The organisation has warned that, in order to meet Scotland's total foster needs, an extra 1,700 foster families would be needed.
Director of Fostering Network Scotland Bryan Ritchie said: "We need the Scottish Executive to implement a limit of three children per foster family, except for larger sibling groups, as is the case in Northern Ireland, England and Wales.
"And secondly, we need more people to step forward and consider becoming foster carers themselves, to provide these children with the care and support they need."
A spokesperson for the executive said: "There are currently no plans to introduce a statutory limit of children in a foster care placement.
"This issue was not included within the Adoption and Policy Review Group's recent report. However, we are aware of this issue and are considering whether a limit would be helpful."
The executive said it has allocated an extra £12m to local authorities over the period 2005-07 to improve recruitment and retention of foster carers.
One council in Scotland has raised the payments it gives to foster carers in an effort to attract more people.
Renfrewshire Council said it would pay carers £353 per child or a pro-rata payment of £50 per child per day for care provided.
Father-of-three Jim Joyce has two foster children and said foster parents should guard against taking on too much.
He said: "We have space here where we could, theoretically, accommodate seven or eight children if necessary.
"But we feel you've got to think of the individual needs of these children and of the needs of your own family.
"It's very important that foster carers think about that. It's not just about how many children they can help out because quantity is not necessarily helping the children."