Now, three weeks after a few hundred people heeded that initial call and rolled out their sleeping bags in a park in New York's financial district, they are being joined by supporters in cities across the US and beyond.
Armed with Twitter, Facebook and shared Googledocs, protesters against corporate greed, unemployment and the political corruption that they say Wall Street represents have taken to the streets in Boston, Los Angeles, St Louis and Kansas City.
The core group, Occupy Wall Street (OWS), claims people will take part in demonstrations in as many as 147 US cities this month, while the website occupytogether.org lists 47 US states as being involved. Around the world, protests in Canada, the UK, Germany and Sweden are also planned, they say.
The speed of the leaderless movement's growth has taken many by surprise. Occupytogether.org, one of several sites associated with the protest, has had to be rebuilt to accommodate the traffic.
OWS media spokesman Patrick Bruner said: "We have on our board right now 147 US cities. I don't know whether they are occupied or they are planning on being occupied. My guess would be over 30 cities are occupied."