A new law banning the sale of tobacco products to anyone under the age of 18 has come into force.
The minimum age to buy cigarettes is being raised to 18
The legal age for buying cigarettes was previously 16 but now any retailer caught selling to under-18s risks a fine of up to £2,500.
It is thought that as many as one in 10 under-15s smoke but prosecution rates for shops which sell cigarettes to under-16's have tended to be low.
The new legislation has been broadly welcomed by health organisations.
MSPs voted unanimously for the move last month, which follows the ban on smoking in enclosed public places which came into force in March 2006.
Minister for Public Health Shona Robison said the new law was "a milestone" in improving the health of young people.
She said: "It sends out a clear message that tobacco is a highly dangerous substance and hopefully prevents young people from taking up smoking in the first place.
"Raising the age to 18 will also make it easier for shopkeepers to identify whether young people are old enough to buy cigarettes, through a passport, a driving licence or a proof-of-age card."
Maureen Moore, chief executive of anti-smoking group Ash Scotland, said research shows that the younger a person starts smoking the more likely it is they will smoke in adulthood.
"Evidence shows that increasing the purchase age can reduce smoking rates, but only if the law is properly implemented," she added.
"We need to equip our local authority officers with the enforcement tools to help them do their job."
The Association of Chief Police Officers in Scotland (Acpos) welcomed the change in the law.
Ch Supt Andrew Laing of Fife Police said: "The health and social benefits will soon become clear.
"Our colleagues in the trading standards departments of local councils will be responsible for the enforcement of the new regulations and will work closely with retailers to ensure compliance."