Palomino 18U League features athletes ranging from ages 17-18. It was started in 1977 after the now-defunct Thoroughbred League was expanded to include 21-year-old players, it ranged from 17-20 previously.

The Palomino World Series was first held in 1980 in San Jose, California with a total of six participants. The inaugural champion was Hayward, California. It wasn't until 1986 that the first international team, Caguas, Puerto Rico, was introduced. That same year was also the first time Greensboro, North Carolina hosted the World Series. The Palomino World Series called Greensboro home for 13 years from 1986-1999 despite Greensboro only being able to win the Palomino World Series in 1994.

Despite international teams entering the World Series in 1986, the first non-US champion was Taipei, Taiwan in 2006. An ironic twist on the victory, the host location was Caguas, Puerto Rico who was the first very international team in the Palomino World Series. It was the second time Caguas hosted the World Series, the other being the year prior. They currently stand as the only international host site. The first ever European Zone Champion joined us in 2019.