The two-volume set LNCS 7439 and 7440 includes the proceedings of the 12th International Conference on Algorithms and Architectures for Parallel Processing (ICA3PP 2012) as well as some workshop papers from the CDCN 2012 workshop held in conjunction with this conference. The 40 regular and 26 short papers included were carefully selected and reviewed from 156 submissions. The CDCN workshop attracted a total of 19 original submissions, 8 of which are included in Part II of these proceedings. The published works cover many aspects of parallel algorithms and architectures, offering both fundamental theoretical approaches and practical experimental results, as well as commercial components and systems.