Jeronimas Kacinskas (or Kacinskas; 17 April 1907 – 15 September 2005) was a Lithuanian-born American composer.
Kacinskas was born in Vidukle, Lithuania (then Kovno Governorate, Russian Empire), to the family of a church organist.
He studied music at the National Conservatory of Lithuania in Klaipeda and at the Prague Conservatory.
He later taught at the State Conservatory in Vilnius.
His Nonet was premiered in London in 1938, and he married Elena Šlevaite in 1941.
In 1944, they escaped from Lithuania and travelled through Poland into Germany, where they were finally rescued by American troops.
In 1949, they arrived in the United States, and Kacinskas became a church organist and choirmaster in Boston, Massachusetts.
From 1967 to 1986, he taught at Berklee College of Music.
In 1991 he was awarded Lithuanian National Prize.