During his career he worked alongside numerous activists, journalists and religious leaders, including Martin Luther King Jr., Saul Alinsky, George McGovern and Studs Terkel.
During World War II, with many young men serving military duty, Hallett began his church career preaching to a congregation in Wall, South Dakota at age 14.
At a Methodist Youth Conference in Clear Lake, Iowa, Hallett roomed with future civil-rights leader James Lawson.
He did a photo study on Boston's Roxbury neighborhood and became acquainted with fellow theology student Martin Luther King Jr. Hallett was influenced by Dean Walter George Muelder, whom Hallett felt "...was way before his time on the status of women in the church, and he had a very strong commitment to dealing with questions of race".
At the Urban Training Center for Christian Mission, Hallett taught organizing strategies to civil-rights activists heading south, as he had noticed: There's a tendency in a movement to go with the flow and respond to problems – we were trying to think ahead...
When you start asking where do you want to be in a year and a half, what are the steps to get there, and what is everyone's role in making that happen, it builds in a discipline that's not externally imposed but that's in the nature of the work.
In 1965, Hallett worked to bring clergy from Chicago and other northern cities to the call of the Civil Rights Movement.
He and other "bishops, rabbis, ministers, priests and nuns felt the call to march in Alabama with Martin Luther King."
Hallett was quoted in the Time Magazine article of Friday, April 9, 1965, entitled Churches: The Selma Spirit—"It was a breakthrough into a whole new spirit," he says, "a sense of being part of a community at a level and depth that we've never known before.
[6] He served as a Founding Board Member for the ShoreBank Corporation from 1973 to 1975, and was vice-president of South Shore's holding company in its critical first five years.
CNT grew from a project at the Center for Urban Affairs examining appropriate technology for city neighborhoods, initially looking at food production, solar energy and conservation.
He taught courses on History of Western Ethics and Political Philosophy, and the Urban Mission of the Church.
The concept for Pathfinder would become a consuming, lifelong interest, stating:It's clear to me that the automobile is a terribly polluting destructive machine.
It is impossible to keep going like this – even the electric cars, the hypercars, are too polluting... Can you imagine what this city would be like if we could convert some of these streets into gardens and tennis courts?
[1]In 1986, Mayor Harold Washington appointed Hallett to the board of the Metra commuter rail system, where he served through 1993.