In the early years of the Johns Hopkins University, Herbert Baxter Adams, a leader of the revisionist school of history, directed the Department of History and Political Science; given under this department were the courses now taught under the Departments of History, Economics, and Political Science. While most of the courses apparently employed historical analysis, a few of the offerings were distinctly political or economic in nature. Visiting instructors supplemented the curriculum; for instance, Thomas M. Cooley, Justice of the Michigan Supreme Court, lectured on torts and taught a Seminary of English Constitutional Law. However, when offered a professorship of jurisprudence in 1880, Cooley declined.

In 1896, Westel W. Willoughby accepted the position of Associate in Political Science. With the death of Herbert Baxter Adams in 1901, the departments separated, leaving Willoughby sole member of the Political Science Department, a position he occupied for nearly twenty years. Although distinct, the Department of Political Science remained closely associated with the History Department. Undergraduate instruction in political science was interdepartmental, and a course in Historical Politics, offered under the auspices of the History Department, was required. Similarly, graduate students were expected to participate in the fortnightly meetings of the Historical and Political Science Association, founded by Adams to encourage the production of original work and the review of current writings.

Alternately with the meetings of the Historical and Political Science Association, Willoughby conducted a political science seminar in which graduate students prepared and discussed original research, generally centering on current events. From 1901 to 1903, topics under investigation included colonial government and international law. The graduate curriculum consisted of six required courses, two of which were offered each year. The first three concerned constitutional law, while the latter three covered the historical development of political ideas.

During the first decade of the 20th century, the department had about twenty graduate students. Apparently, they were prolific readers and writers, for, in 1906, the department published 70 pages of excerpts from papers delivered at the political science seminary. Most of the papers dealt with recent events, such as the Russo-Japanese War.

From Willoughby's repeated pleas to President Goodnow (printed in the Circulars) it is apparent that he wished to expand the department, particularly in the area of undergraduate instruction. During the 1910s, limited expansion, in the form of more courses per term, was possible. From approximately 1914 to 1916, Dr. James Brown Scott lectured without pay on the subject of international law. Willoughby repeatedly petitioned the University to appropriate money for Scott's salary and for a chair in government and administration. Although these efforts were unsuccessful, the University did, in 1917, appoint Arthur C. Millspaugh, a Johns Hopkins Fellow, to an instructorship in political science.

In the 1920s, the department continued to expand. William F. Willoughby, Westel Willoughby's brother, was a lecturer in public administration and taught several courses, as did President Goodnow. In all, thirteen graduate level courses were offered.

In accordance with Willoughby's wishes, the department increased the number of courses for undergraduates. The four introductory courses in 1926 were given by John H. Latane, who held a dual appointment as professor of American History and lecturer on international law, and Samuel James Hart, who was made an Associate. Walter Wheeler Cook, later of the Institute of Law, was a visiting lecturer.

Undergraduate education was further expanded in the late 1930s; with four full-time faculty members, Drs. Hart, Mattern, and Weinberg, and Mr. Sachs, the department gave seven undergraduate courses. Also at this time, the requirements for a B.A. in political science became more extensive. In addition to taking every political science course offered, political science majors were obliged to become acquainted with the basics of economics and history. To graduate, they were required to pass a comprehensive examination, including in its scope: American government and politics; Elements of American constitutional law; Modern governments outside the U.S.; International law and relations; History of political thought; Relation of government to economics and social relations; and Any additional topics chosen by the department.

In response to the declining enrollment brought about by depression and the war, the department encouraged faculty members to participate in community affairs. With only six graduate students and nine undergraduates, the department still offered a total of fifteen courses.

By 1946, the department could boast five professors: Carl B. Swisher, Owen Lattimore, V. O. Key, Johannes Mattern and Malcolm Moos. With the return of World War II veterans eager to complete their interrupted educations, the department, in 1947, offered sixteen graduate level courses.

Although the department was greatly pleased with the high quality of graduate work, which it attributed to the influx of veterans, the faculty felt that, with twenty graduate students, the department had reached its limit if a rigorous standard of quality was to be maintained. Accordingly, over the next few years, the department stiffened its admissions criteria and restricted enrollment to about fifteen students.

During the 1950s, changes in the faculty left the department with a total of six faculty members, four of whom were relatively new. By 1956, Thomas I. Cook, Robert W. Tucker, Francis Rourke and Gottfried Dietze had joined the department. At this time, the department instituted a senior essay, essentially a thesis, prepared in consultation with a faculty advisor. Undergraduate enrollment increased so much that, in 1957, the department offered sixteen undergraduate courses.

By the mid-1960s, the department had almost doubled in size. With eleven faculty members, in 1966, the department offered sixteen graduate courses, seventeen undergraduate courses and eighteen courses suitable for both groups. Within the department, work was divided into six classifications: Public law and jurisprudence; Comparative government and politics; American parties and politics; Public administration and state and local government; International politics, law, and organization; and Political theory. One year later, the department again expanded; two new faculty members were hired.

By 1976, the department had a faculty of eighteen, capable of offering a total of eighty-seven courses (twenty-seven graduate, seventeen undergraduate, and forty-four intermediate). Faculty members began to teach courses in political sociology, judicial behavior, and urban politics. In the late 1970s, the department began to permit seniors to substitute three intermediate level political science courses for the senior thesis. Participation in two introductory courses and two political theory courses was required, and students also had to complete eight elective courses. In 1981, with fifteen faculty members, the Department of Political Science listed in its catalog a total of seventy-nine courses (twenty-seven graduate, thirteen undergraduate, and thirty-nine intermediate).