In 1995, having established a successful law practice, Costas sought and won an at-large seat on Valparaiso City Council. While on Council, Costas supported a measure banning the sale of certain forms of pornography in Valparaiso. Costas also cast a vote against allowing city employees to organize into a public employee labor union, though he received labor union endorsements in subsequent elections. In 1997, as Chairman of the Parks Foundation, Costas led an effort to raise $250,000 to buy land for a park on Silver Lake.