Let f W A ! B be a ring homomorphism and J an ideal of B. In this paper, we initiate a systematic study of a new ring construction called the "amalgamation of A with B along J with respect to f ". This construction finds its roots in a paper by J. L. Dorroh appeared in 1932 and provides a general frame for studying the amalgamated duplication of a ring along an ideal, introduced and studied by D'Anna and Fontana in 2007, and other classical constructions such as the A C XBOEX and A C XBOEOEX constructions, the CPI-extensions of Boisen and Sheldon, the D C M constructions and the Nagata's idealization.