Lester A. Salamon labels four "impulses" of nonprofits that pull in opposing directions, and which bring clarity to the heart of the struggle for the soul of the American nonprofit sector.

"A struggle is under way for the “soul” of America’s nonprofit sector, that vast collection of private, tax-exempt hospitals, higher-education institutions, day care centers, nursing homes, symphonies, social service agencies, environmental organizations, civil rights organizations, and dozens of others that make up this important, but poorly understood, component of American life.

"This is not a wholly new struggle, to be sure. From earliest times nonprofits have been what sociologists refer to as “dual identity,” or even “conflicting multiple identity,” organizations.1 They are not-for-profit organizations required to operate in a profit-oriented market economy. They draw heavily on voluntary contributions of time and money, yet are expected to meet professional standards of performance and efficiency. They are part of the private sector, yet serve important public purposes.

"In recent years, however, these identities have grown increasingly varied and increasingly difficult to bridge, both in the public’s mind and in the day-to-day operations of individual organizations. In a sense, America’s nonprofit organizations seem caught in a force field, buffeted by a variety of impulses, four of which seem especially significant. For the sake of simplicity I label these voluntarism, professionalism, civic activism, and commercialism, though in practice each is a more complex bundle of pressures."--Lester Salamon, Nonprofit Quarterly