“The Grass Roots weren’t the hippest band on the block,” The Boston Globe wrote in 1989. “But they were — and remain — a sure-fire guilty pleasure, a blissful package of pure pop.”

The group’s longest-serving member, Mr. Grill appeared with the Grass Roots for more than four decades: first in the group’s heyday and again as the band has enjoyed a renaissance on the oldies circuit. His voice — high, sweet and supple — was memorably urgent and beseeching in the group’s many songs of love.

He also played bass and wrote some of the group’s songs, though the Grass Roots’ best-known material was written primarily by nonmembers.

The Grass Roots began life as a phantom. In the mid-1960s, two Los Angeles songwriters, Steve Barri and P. F. Sloan, were asked by their label, Dunhill Records, for songs that would capitalize on the growing appetite for folk-rock.

They wrote “Where Were You When I Needed You” and, as the Grass Roots, recorded a demo. When the song had some success on the radio, they cast about for an existing band to become the Grass Roots.