Tamassia received a laurea (the Italian equivalent of a M.S. degree) from the University of Rome "La Sapienza" in 1984, and a Ph.D. from the University of Illinois at Urbana-Champaign under the supervision of Franco Preparata in 1988. He then took a faculty position at Brown; he has also held visiting positions at the University of Texas at Dallas, the Consiglio Nazionale delle Ricerche, and La Sapienza.

Tamassia has nearly 200 publications and is an ISI highly cited researcher. He was one of the original organizers of the International Symposium on Graph Drawing, and was co-chair of that conference in 1994; he has also been co-chair of the semiannual Workshop on Algorithms and Data Structures (1997, 1999, and 2001) and the annual Workshop on Algorithms and Experiments (2005). He is founding editor-in-chief (since 1996) of the Journal of Graph Algorithms and Applications as well as belonging to several other journal editorial boards.

In 2006, the IEEE Computer Society gave Tamassia their Technical Achievement Award "for pioneering the ?eld of graph drawing and for outstanding contributions to the design of graph and geometric algorithms." In 2008, he was elected as an IEEE Fellow.