Board of Equalization member Betty Yee said friends of Vasconcellos learned of his death early Saturday afternoon.
"Difficult day for many, myself included," Yee said.
Former lawmaker John Burton called Vasconcellos a "man of great heart, of great intellect and great compassion."
"John wore his compassion on his sleeve," Burton said, describing Vasconcellos as the Legislature's "conscience on the budget" and other issues.
"The bad part is he has left us. The good part is that he isn't suffering," Burton added of his former colleague.
Vasconcellos served from 1966 through 2004 in the Assembly and Senate, and for many years chaired the powerful then-Ways and Means Committee in the Assembly. He carried legislation on topics ranging from improving students' self esteem and improving the higher education system to increasing patients' access to medical marijuana.
Former lawmaker Art Torres said in an e-mail that Vasconcellos "was like a big brother to me and my family and especially my son Joaquin."
"I'm heartbroken," Torres said Saturday.
PHOTO: Former state Sen. John Vasconcellos, D-Santa Clara, makes a telephone call from the floor of the Senate chambers in February 2003, during his final term in the Legislature. The Sacramento Bee / Dick Schmidt