In brief - such laws do exist, but do not appear to be rigidly enforced. Hopefully resident legal experts Fabio or Alberto Guzm?n can provide the exact legal details.
It really depends what you have in mind. Feel free to PM if you don't want to discuss specifics on the board. I know from experience, from working with three international development organisations here in the DR, that certain organisations with a presence in the DR have never actually officially registered but are still able to operate. They are still official and above board in as much as they have to comply with DR employment law, have bank accounts, pay taxes where applicable, etc.
Those who are registered get some perks, like quasi-diplomatic status for their foreign employees, who get to carry a little blue 'carnet' allocated by the Ministry of the Exterior which they can presumably use to wave at AMET officers to get out of sticky situations. They also get to use the diplomatic/VIP lounge at the airport.
As for local outfits, there are some genuine charitable/voluntary/civil society/environmental/campaigning organisations doing excellent work, but the term NGO (ONG in Spanish) is also used to define what are in effect clientilism slush funds run by every two-bit politician. - I'm having to learn to use alternative terms because "NGO/ONG" is forever tainted as a result.
