The welfare definition of economics is an attempt by Alfred Marshall, a pioneer of neoclassical economics, to redefine his field of study. This definition expands the field of economic science to a larger study of humanity. Specifically, Marshall's view is that economics studies all the actions that people take in order to achieve economic welfare. In the words of Marshall, "man earns money to get material welfare." Others since Marshall have described his remark as the "welfare definition" of economics. This definition enlarged the scope of economic science by emphasizing the study of wealth and humanity together, rather than wealth alone. In his widely read textbook, Principles of Economics, published in 1890, Marshall defines economics as follows:

Political Economy or Economics is a study of mankind in the ordinary business of life; it examines that part of individual and social action which is most closely connected with the attainment and with the use of material requisites of well-being.