The Rival Rigelians, by Mack Reynolds

A group sets out from Earth to Rigel, where they will secretly influence events on two lost colony worlds to bring their civilizations up to the point where they can join the Galactic Commonwealth. A disagreement on how to proceed sharply divides the group, so they agree to split their forces: one group will work on the planet Genoa and use capitalistic means; the other will bring communism and a command economy to the planet Texcoco. Who will win? Which planet will advance faster?

The events on Texcoco involve a lot of bloodshed to unite the disparate tribes and force them to industrialize. On Genoa there are problems too: unbridled capitalism brings winners and losers as well. But in the end, it's the Rigelians who are the winners: they realize they are being manipulated, and the two planets develop enough space travel to visit each other, join forces, and kick out the interloping Earthers. Genoa and Texcoco will develop their own economic and political systems, thank you very much. Earthmen, go home.