Scotland's first independent regime of charity regulation came into force on Monday with the introduction of the Charity Test.
New charities must meet the two-part test, demonstrating that they pursue at least one charitable purpose and provide public benefit.
The test will be enforced by the Office of the Scottish Charity Regulator, which will also maintain a 20,000-strong register of charities.
It will be an offence for an organisation to "hold itself out to be a charity" if it is not entered in the register.
Jane Ryder, chief executive of the OSCR, said: "For the first time in Scotland, we have legislation specifically created for the charity sector.
It is essential the public has confidence in the governance and regulation of charities, and that charities can flourish, secure in the knowledge of their rights and responsibilities."
The test will be applied to all charities registered with HM Revenue & Customs. They must satisfy the regulator that the benefits they offer the public are not "unduly restrictive".