This report represents the results of the first phase of the work of the Language Structure Group. The goal of this work is to arrive at a proper structure for a machine-independent problem-defining language, at the systems level of data processing. The report is based, for the most part, on a mathematical model called "An Information Algebra" developed primarily by R. Bosak. It is hoped that this report will be read (a) with avid interest by programming language designers and implementors, and all those interested in developing a theoretical approach to data processing; (b) with interest and understanding by professional programmers and systems analysts; and (c) with appreciation by the businessman-analyst-manager. The authors have not attempted an exhaustive discourse in this report. Rather, they have tried to present a philosophy to the professional people who are vitally concerned with providing a working language for the systems analyst's use. They trust that the ideas in this report will stimulate others to think along similar lines. Questions and comments will be welcomed, and can be addressed to any of the members of the Language Structure Group: Robert Bosak, System Development Corporation Richard F. Clippinger, Honeywell EDP Division Carey Dobbs, Remington Rand Univac Division Roy Goldfinger (Chairman), IBM Corporation Renee B. Jasper*, Navy Management Office William Keating, National Cash Register George Kendrick, General Electric Company Jean E. Sammet**, IBM Corporation