Gardaí will conduct a national speed enforcement operation over the next 24 hours.
National Slow Down Day will include more than 1,000 speed enforcement zones and road safety messages on social media.
Almost 70 people have lost their lives on the country's roads so far this year.
Experts say a 1% reduction in speed will bring about a 4% decrease in fatal accidents.
Director of Consumer Affairs at AA Ireland Conor Faughnan said the initiative highlighted the need for a stronger police presence on our roads.
He said: "It's a pity it's only one day. The cynic says it's a bit cosmetic...but it does do good. It indicates the sort of presence we should be expecting from gardaí every day of the week."