Synchronicity: An Acausal Connecting Principle, by Carl Gustav Jung, is a book published by Princeton University Press in 1960.

[1] Jung was intrigued from early in his career with coincidences, especially those surprising juxtapositions that scientific rationality could not adequately explain.

He discussed these ideas with Albert Einstein before World War I, but first used the term synchronicity in a 1930 lecture, in reference to the unusual psychological insights generated from consulting the I Ching.

A long correspondence and friendship with the Nobel Prize-winning physicist Wolfgang Pauli inspired a final, mature statement of Jung's thinking on synchronicity, originally published in 1952 and reproduced in this book.

Together with a wealth of historical and contemporary material, this essay describes an astrological experiment Jung conducted to test his theory.