James C. Hagan will succeed Donald A. Williams as chief executive officer of Westfield Financial, the holding company for Westfield Bank, effective Dec. 31.

Hagan has served as president and chief operating officer of the Westfield Financial and Westfield Bank since June 2005. Prior to that, he had served as senior vice president and commercial loan department manager of the bank since 1998. From 1994 through 1998, Hagan was a vice president of the bank.

Williams will continue to serve as chairman of the board of the company, a position he has held since 2005. Williams served as president of the bank since 1983 and as chief executive officer of the bank since 1987. Williams has served as chief executive officer of the holding company since its inception in 2001.

In addition, the company announced that Leo R. Sagan Jr. will succeed Michael J. Janosco Jr. as chief financial officer and treasurer, effective Dec. 31. Sagan has served as controller of the bank since 2002 and as vice president since 2003.