James B “Jim” Prendergast was born on August 23, 1916 in Brooklyn, New York. He played baseball for Brooklyn Technical High School team and was signed by the Dodgers upon graduation and sent to Hartford but didn't play.

"Bob [Quinn, Dodgers GM] got me a job playing semi-pro ball up around York, Pennsylvania," he told The Sporting News on April 21, 1948, "where Gene McCann, Yankee scout, saw me and asked me if I'd like to sign with the Yankees. I nearly fainted dead away, but before I did, I signed."

Prendergast played for the Butler Yankees of the Penn State Association in 1936. He advanced from Class D to Class B the following year when he joined Augusta at the start of the season, but despite an 8-6 record with Augusta he was sent back down to Class D ball with Palatka of the Florida State League.

In 1938, Prendergast joined Birmingham of the Southern Association. He was 3-3 in 12 games for Birmingham and also pitched for Seattle and Hollywood of the Pacific Coast League that year. In 1939, Prendergast began a three-year association with Little Rock of the Southern Association. In 1941 he was 15-16 with a 4.14 ERA. It was his last season before four years of military service. 

Prendergast had originally been classified 4-F but was reclassified by his draft board in February 1942, passed his Army physical and was inducted on April 1, 1942. Stationed at Fort Benning, Georgia, he pitched for the Fort Benning Infantry School All-Stars and beat his old team, the Birmingham Barons, 7-2, on April 11, 1943.

He attained the rank of lieutenant in December 1943, and continued to play baseball at Fort Benning in 1944 with the First Student Training Regiment Wolves. The team included Brooklyn's Boyd Bartley.

Attaining the rank of captain he later served in France, southern Germany and Austria with the 36^th Infantry Division, and played ball with the 36th Infantry Division Texans team after Germany surrendered. On July 24, 1945, he played against the 106th Infantry Division at Karlsruhe, Germany, in a game dedicated to comrades lost during the Ardennes campaign. 

"In 1946 I worked out with Cincinnati," he recounted in The Sporting News on July 3, 1957, "and one morning Giles told me he was sending me to Syracuse. I told him he couldn't because of the GI Bill of Rights. I said it required them to keep me for a year. Then I learned baseball had its own GI Bill, one month. It was a stronger bill than any Congress could make, I guess. Anyway I called Happy Chandler. Mr Chandler said: 'Now, James, we're going to take care of all servicemen.' They took care of me. I was sent to Syracuse."

Prendergast was 17-10 with Syracuse in 1946 and was 20-15 with the club in 1947 but left the Reds’ organization and was signed by the Boston Braves. He made his major league debut with Boston on April 25, 1948 and made 10 appearances for a 1-1 record. By July 1948 he was with Milwaukee of the American Association where he was 5-8. 

Prendergast was back with Syracuse in 1949. On opening day April 23, 1950, he narrowly missed throwing a no-hitter for the Chiefs, allowing just one hit in the ninth inning with two out. Only five balls reached the outfield as Syracuse defeated Buffalo 4-0.

In 1951 he filed a $150,000 suit against Organized Baseball accusing them of trying to maintain a monopoly "by having the right to blacklist any major league player for five years for violation of the reserve clause and to continue his ineligibility for an indefinite period."

Prendergast questioned the legality of the Reserve Clause that binds a player to one club until he is either transferred or his contract cancelled. He questioned the right of the Syracuse club, after a salary dispute, to transfer him to the Beaumont (Texas League) club and his suspension for failure to report. He claims his potential earnings would have been at least $50,000 but the restrictions of the reserve clause, and triple damages were sought under the provision of the anti-trust law. This lawsuit was dismissed but he started another claiming he was barred from playing in Cuba after his suspension.

Jim Prendergast never played organized baseball after the 1950 season. He became a beer salesman in Buffalo and passed away in Amherst, New York on August 23, 1994 – his 78^th birthday.