Fortuna Primigenia is an old Goddess of fate and luck in Roman myth whose worship was centered around the city of Praeneste, the modern Palestrina in Italy. Praeneste was a city of the Latini tribe in the region of Italy named Latium for them, and was located about twenty miles south-east of Rome on the coast of the Tyrrhenian Sea. There Fortuna Primigenia had a great temple complex and an oracle, appropriate to a Goddess of Fate.

Her name was often interpreted as "First-born" or "Eldest", and taken to mean that She was the eldest daughter of Jupiter; so She was also called puer Jouis, or "Child of Jupiter". However, the title Primigenia should be more properly taken to mean "Primordial" or "Original" Fortune, as it refers to the antiquity of Her worship at Praeneste, which was older than that at Rome. As Praeneste was often at odds with Rome during the Republic, and not made part of Rome until the first century BCE, Fortuna Primigenia was regarded as a "foreign" Goddess by the somewhat xenophobic Romans, though they did come to embrace Her in time.

As the "First-born" daughter of Jupiter, Fortuna Primigenia was believed to fix the new-born child's destiny or fate. Her name could also be interpreted as "First-bearer", as in the first to bear children; and She was depicted as suckling two infant children, who were said to be Juno and Jupiter, i.e., the supreme female and male principles, symbolizing totality as Mother and Father Deities. Naturally as a Goddess connected with childbirth, She was especially favored by married women.

Her temple complex in Praeneste was built into the side of a great hill, and had several levels of terraces and staircases, a basilica, and curia (meeting-hall), with the small circular temple to Fortuna at the top. It was a huge complex, measuring 1300-plus feet at the base of it and stretching vertically up the hillside for 450 feet, and it incorporated two reservoirs which provided water for a great fountain as well as for the surrounding town. The ruins today are very impressive, though a palace was built on the foundations in the Renaissance; following the original layout, it kept the semicircular shape of the colonnade just below the temple (alas, the temple itself has long since vanished), as is not uncommon of medieval or Renaissance structures built over ancient sites, since it's easier to built on foundations that are already there than to take them apart and start from scratch. On the oldest level, that of the basilica, are two small caves or grottoes, the one to the west most likely being the original shrine of Fortuna around which the complex was built. The temple of Fortuna Primigenia was one of the largest in ancient Italy, if not the largest, and owing to its spectacular situation on a hill, could be seen from all over Latium, even from as far away as Rome.

The Oracle of Fortuna at Praeneste was of a fame to rival Delphi's, and was called the sortes Praenestinae, or "the Praenestine lots". According to legend, one Numerius Suffustius was told in a dream to delve into the stone at a certain spot in Praeneste. When he did just that, he found some mysterious pieces of oak inscribed with sayings written in an archaic alphabet. These tablets were then kept in a box and used at the oracle to Fortuna established there: when the oracle was to be consulted, a young child went to the box and, after shaking it, picked one of the tablets at random. He then gave it to the questioner, who was left to interpret the meaning for him or herself. The Oracle at Praeneste remained popular for centuries and was only closed down in the reign of the Christian Emperor Theodosius in the 4th century CE.

Like Fors Fortuna, Fortuna Primigenia had several temples in Rome. One of these was on the Capitoline Hill and was traditionally ascribed to Servius Tullius, an early king of Rome who had been born a slave and risen to be king, and who had also built a temple to Fors Fortuna by the Tiber. Three more temples to Fortuna gave their name to a neighborhood on the Quirinal Hill, the tres Fortunae, located just by the gate of the porta Collina; one of these temples was dedicated to Fortuna Publica, ("Fortuna of the People"), but the other two were to Fortuna Primigenia. The largest of the three was given to Fortuna Publica Populi Romani Quiritium Primigenia ("First-born Fortuna of the Roman Nation, its People and Citizens"), Her name and titles as they were officially known in Rome, and dedicated in 194 BCE on May 25th, which thereafter became its festival day. The third temple, of which there is not much known, had its festival day on November 13th.

Fortuna Primagenia's worship was originally centered in a grotto, a small cave (it is related to the word crypt) of a type celebrated in Italy for being a cool and refreshing place out of the sun; often water is found in grottoes. Fortuna's Praenestine grotto likely did have a spring or other form of water in it, and it had been decorated with a great mosaic in its floor that depicted the Greek Sea-God Poseidon, who was equated with the Roman Neptune, originally a God of fresh waters. Caves are a symbol of the earth and the Earth-Mother; they are additionally gateways to the Underworld, and connect the lands of the living and dead, the lands of mortals and the Gods. Oracles are frequently found at sites that have caves or springs or that otherwise connect to the interior of the earth through such features as natural fissures or volcanic vents (as is the case at Delphi). Given this, Primordial Fortune can be seen as an ancient chthonic Goddess, an Earth-Mother Who has the power to give abundant good things from Her earth—gold, silver, gems, plants, animals, a bountiful harvest, success and good luck—and Who can predict the future that She sets as a Fate-Goddess Who controls the life, fortune, and death of all.