In Ontario, Canada, there is no specific age set by law that dictates when a child can stay home alone. However, the Ontario Ministry of Children, Community and Social Services provides guidelines suggesting that children under the age of 10 should not be left alone, while those between the ages of 10 and 12 may be left alone for short periods of time. Ultimately, the decision depends on the child's maturity, ability to take care of themselves, and the specific circumstances. It's always a good idea for parents to use their judgment and consider factors like the child's level of responsibility and the safety of the environment.