I recommend Lew Daly's article, In Search of the Common Good: The Catholic Roots of American Liberalism, from the current Boston Review. Writing for a largely secular, progressive audience, Daly tries to bring some coherence to the increasingly popular "common good" by focusing on John Ryan and the role of CST in the New Deal. Daly concludes that:
Catholic social teaching had revolutionized the moral landscape of capitalism, not only by reinforcing the progressive critique of laissez-faire constitutionalism but, more importantly, by stealing the thunder of higher-law reasoning and restoring its communal roots. It was a turning point that made the welfare state morally necessary and, because of that, politically possible.
As for what happened to the "common good" after the New Deal, Daly writes:
Sexual freedom, extreme secularism, and other agendas of the new social liberalism did not merely replace the common good as a normative framework. It shifted the whole framework of rights from the worker and his family and community, viewed as something in need of protection, to the detached individual of liberal philosophy, regardless of economic position or need. Essentially, the common good was supplanted by individual liberation, and what remained of it in public discourse was little more than empty rhetoric (think “compassionate conservatism”).
New Deal liberalism’s common-good ideal gave workers and their families a new (yet very old) moral ground for claiming resources and power necessary for their self-preservation. . . . The individualistic social liberalism that came to dominate decades later clearly weakened, and in some ways fundamentally attacked, the familial and communal understanding of rights that shaped New Deal social policy. The protection of the family and the home from economic tyranny was no longer a certain or even desirable policy objective in an era of individual liberation marshaled against the traditional culture of family and community. Not coincidentally, as the common good disappeared from the discourse of rights in the 1960s, big business re-established its dominance in American politics, and families and communities received no new protection from the government even as older protections came under attack. The family living wage paid by a substantial majority of U.S. businesses literally vanished from the country by the late 1970s.
Daly concludes that the religious dimension of the common good was crucial to its vitality, and that "reviving a secular version of the common good" will not "guide us from chaos to community."