The Dispossessed (1974)

Shevek leaves an anarchist society to visit a wealthy neighbouring world, forcing him to examine both the freedom his home offers and the pressures it denies. Le Guin makes cooperation something a community must keep renewing, because even a society without formal rulers can punish dissent. This is the most searching choice here for readers interested in institutions rather than a perfect blueprint. Its optimism lies in keeping exchange and criticism possible.