Liber, in his original Roman conception, was probably a god who presided over male fertility and especially the act of ejaculation. Like the name of his counterpart deity Libera, his name is derived from the Latin word that meant "liberation". A cult that worshiped the phallus in the name of Liber was practiced in Lavinium and later brought to Rome (Spaeth 8). Allegedly, the phallus was carried about the countryside for a month in a wagon, and during that month the citizens were allowed to indulge in saying obscene words in public until the phallus was carried through the forum and put in its resting place. Then respected matrons would crown it publically with wreaths, which would drive evil enchantments away from the fields. A representation of the human phallus was supposedly kept in the temple of Liber (Dumezil 378).
The Liberalia is celebrated in his honor, along with his counterpart deity Libera, on March 17. A major part of the festival featured old women called sacerdotes Liberi wearing crowns of ivy selling honey cakes in the street. The cakes were fried on portable hearths, and a part of each cake bought was offered to Liber in the name of the buyer. Young men who have reached seventeen years of age also gain the right to wear man's clothing, the toga uirilis or liber, during this festival (616).
After the formation of the Aventine triad, he absorbed the mythology of Dionysus (Spaeth 26). He may or may not have been the god of wine before this took place (Dumezil 378). Liber also shared a temple with Hercules on the Quirinal, erected by the emperor Septimius Severus. That temple was the second largest ever built in Rome, with columns over 21 meters high and a central square that covered 13,000 square meters. The gods were paired in the new cult because they were the patron gods of the emperor's birthplace at Lepcis Magna in North Africa (Beard 255).
While Liber is often identified with the god Bacchus, whose worship became subject to Senate control, Liber himself never seems to have been viewed as particularly dangerous or subversive (255).