Membership figures for the Association cannot be considered entirely apart from recurring financial problems and other issues, but the statistics may be summarized separately. At the organizing meeting on December 31, 1930, 42 people signed up as members. According to the preliminary constitution adopted that day, charter membership was accorded to all those who enrolled by June 1931, and 461 names were on the rolls by that time. At the end of the year there were 494, but more than 100 names had to be dropped at the close of 1932. Vigorous efforts to recruit new members were begun in 1933 under the leadership of Homer Dodge, and by 1934-35 the membership had risen to more than 700. The Association continued to gain members, gradually but steadily, with R.C. Gibbs, Lloyd Taylor, and Marsh White as successive chairs of the Membership Committee. By 1950 the figure was more than 3,000. White was particularly active in recruiting student members.

Marsh White resigned as chair in 1951, and the figures leveled off: It was reported by the Secretary that during 1952 there was a net loss of 300 members. Some 200 had joined that year, but there were roughly 500 resignations, "primarily because many teachers are going into industry," according to the Executive Board minutes. The absence of vigorous recruitment was undoubtedly responsible in part for the failure to replace the defecting members, but we have also noted that there was a slump in the demand for academic physicists in the early 1950s immediately after the bulge following World War II. By 1955, however, the trend had been reversed and AAPT membership climbed steadily up through 1970, when the number reached a maximum of about 13,000. The success of membership campaigns depends a great deal on the objective situation, a healthy demand for physics education itself, but the vigorous efforts of a succession of Membership Committee chairs, including Ralph P. Winch, A.A. Bartlett, and C. Luther Andrews, must be given part of the credit. The Membership Committee, as a recruiting body, has since been phased out.

The constitution of AAPT was amended in 1938 to broaden the qualification of membership and to establish a new category of members, called "junior" until 1976 when the more appropriate term "student" was authorized. This component of AAPT membership was as high as 29% in the late 1980’s, but has fell drastically in the next decade. By 2002, it had reached 7%.
Informally, the Association now has contact with physics students through the Society for Physics Students, but historically the involvement of students was effectively encouraged by Marsh White during his direction of the AAPT Membership Committee because of his connection with the physics honor society Sigma Pi Sigma. This society was founded as a local honor organization at Davidson College (North Carolina) in 1921, and began to emerge as a national society in 1925 with the establishment of additional chapters. Professor White became its executive secretary in 1930, and after 1938 he saw to it that Sigma Pi Sigma circulated its members regularly and offered a cash subsidy to members who wished to join AAPT. In 1950 the American Institute of Physics established student sections as part of its Education and Manpower Division; in 1968 Sigma Pi Sigma joined with these student sections to form the Society of Physics Students (SPS). The Executive Board of AAPT took a keen interest in this merger, although the dual society operates within AIP and is not formally related to AAPT. There are several hundred SPS chapters in educational institutions throughout the country, and of these, about two-thirds are associated with chapters of their honor component, Sigma Pi Sigma. There is a contributed SPS paper session at the AAPT summer and winter meetings.

The first four emeritus members of the Association were granted that status in 1943. Only 10 years of membership were needed to qualify at that time, if the member was at least 60 years old and retired from regular employment. Twenty years of regular membership are now required for emeritus members. The number of emeritus members is rising rapidly. In 1998 there were 644 emeritus members, comprising 8% of the membership. In 2002 there were 1152 emeritus members, comprising 11% of the total membership.
Since the late 1950s, "persons, corporations, and institutions shall be admitted to sustaining membership." Because individuals have never applied for such membership the category now no longer includes "persons," and Sustaining Members are corporations having an interest in the improvement of physics education. Dues paid by Sustaining Members have varied somewhat; the figure is now (2002) $650/year. At one time there were as many as 30 corporations, although the number fell to less than half that in the 1970s. There are now 28 Sustaining Members. Typically they have been textbook publishing companies or makers of scientific instructional apparatus, but there have been other companies as well. AAPT has benefited by the cooperation as well as the financial support of its Sustaining Members.

Except for small positive fluctuations in 1972 and 1974, the membership of AAPT gradually declined between 1970 and 1980 before resuming a modest upward trend. At this time (2002) membership stands at 10,000. External factors were clearly responsible for the decline: Physics education had lost its priority status, the demand of physicists (and physics teachers) had failed to keep up with production, and the number of students at various levels had fallen off. According to the Manpower and Statistics Division of the American Institute of Physics, from 1972-85 the number of doctorates earned annually in physics has fallen from 1335 to 971, a decrease of more than 40%. During the same period the annual production of bachelors has dropped from nearly 6,000 to 4,500, some 23%. These declines have reversed in the last few years. In 1988, 1,150 doctorates in physics were earned and 5,152 bachelor degrees in physics were awarded. All the older societies in AIP faltered in membership around 1970 as well, but most of them have recovered, at least partially.

In the words of Homer Dodge, the first AAPT President, "finances were a serious problem right from the first minute. One reason was that physics teachers, then and now [1963] don't have much money." It was generally felt at that time that the primary organizational duty of a serious physics teacher was to become a member of The American Physical Society. The dues for AAPT were set at $2 in the beginning, so a person could belong to both societies without too much strain. (APS membership dues were $10 and APS fellows were charged $14.) The Association could hardly launch a membership journal on such a meager income, and the Executive Committee recommended a raise to $3 beginning in 1933 to help finance the new publication. Since the original dues were prescribed in the bylaws, it was necessary to submit the new figure to the members, who approved it by mail ballot in January 1933. By 1935 the financial situation was even tighter, but there was reluctance to raise the regular dues; instead the Treasurer was authorized to "accept as annual dues $7.50 from 'contributors' and $15 from 'sustainors'." The device did help a little: of 862 members the next year, 48 were "contributors" and 10 were "sustainors." The dues for 1938 were raised to $5, and it was decided that "contributor" and "sustainor" be held in abeyance. Junior members, authorized in 1938, paid dues of $2.50.

Some relief came in the form of a grant of $7,500 from the Carnegie Corporation in December 1937. This grant, obtained through the efforts of F.K. Richtmyer "to further the development of the American Physics Teacher," was to be used at the rate of $1,500 per year for five years. For 1937 the journal expenses alone were $3,000, approximately $500 more than the total dues income, but in 1938 the budget was balanced and the deficit was wiped out.

Thus matters stood until after World War II, when physics education was expanding. Early in 1947 it was decided that regular members should pay $6 and junior members $3, effective in 1948. At the annual meeting of January 30, 1954, a change was made in the bylaws to permit regular dues up to $8 and junior member dues up to $4. Actually the regular dues went only to $7.50 and remained so until 1965 when they were raised to $10. At that time, dues for junior members were made $6.

The Association survived and remained active, but its funds were modest. Francis Sears sometimes recalled in later years that when he became Treasurer in 1952, the budget was prepared at a portable blackboard during annual Executive Committee meetings; records show that the first budget he proposed was $18,600. As of 1997, the gross expenses amounted to about $4.2 million. It is true that the consumer price index has risen by a factor of four since 1952, but services to members and other physics teachers have multiplied by an order of magnitude. Most of these new services have been introduced within the past 10 years, with the expansion of the Executive Office and wider committee activity.

Until recently the maximum annual membership dues were set in the bylaws, but the present constitution provides merely that annual dues for regular and student membership shall be determined by the Executive Board. Annual dues for Sustaining Members are also determined by the Executive Board, but "shall not be less than $200."

Revisions and extensions of the constitution have been necessitated from time to time, largely by the expansion of Association activities. Most often the changes have been piecemeal, made to answer specific needs. In 1979, the membership accepted a revision. In 2000, the membership approved another revision. Three major changes emerged from this revision. First, procedural matters and operational policies were separated from the Constitution so that the Constitution became the fundamental framework of AAPT and its governance. Second, the Executive Board was clearly identified as AAPT’s governing body and corporate Board of Directors. Finally, the role and continuity of the Section Representatives on the Executive Board was increased by including both the chair and vice chair on the Board with successive two-year terms.

The latest version was accepted by the membership late in 1979. The person mainly responsible for seeing that inconsistencies, anachronisms, and ambiguities were eliminated by the time of the 50th anniversary of the Association was James Gerhart, acting as a member of a task force on review chaired by Janet Guernsey. No large changes in the structure or method of governance of AAPT seemed called for at that time.