The decade from 1930 to 1940 was a period of expansion; there were seven chapters at the opening of the period and fifteen at the end. At the 1932 conclave, Theta Chapter was established in Elizabethtown College in Elizabethtown, Pennsylvania. A charter was also granted to a group at the Indiana State Teachers College at Terra Haute, Indiana. However, this latter chapter (Iota) failed to organize and was never formally installed. Kappa Chapter was chartered in 1935 at Western Illinois State Teachers College in Macomb, Illinois. During the following year, Lambda Chapter was chartered at the State Teachers College in Mansfield, Pennsylvania. In 1937, petitions were approved for Mu Chapter at the State Teachers College in Mankato, Minnesota, and for Nu Chapter at Northern Illinois Sate Teachers College in DeKalb, Illinois. Xi Chapter was chartered at Ball State Teachers College in Muncie, Indiana, in 1938, and during the following year a charter was granted to Omicron Chapter at Wilson Teachers College in Washington D.C.

The fifth conclave of the society was held on the campus of Otterbein College on April 11 and 12, 1930; here for the first time at a national meeting, chapter sponsors met for a discussion of chapter problems. The following year the conclave met at Stevens Point, and again much attention was given to internal affairs of the society by faculty sponsors. The 1932 conclave at Cape Girardeau determined a number of important phases of the society's affairs. An official jeweler was selected, and a coat-of-arms was designed by Dr. Henry W. Olson of Eta Chapter was officially approved. (This deign was never much used, and has been lost.) At this meeting the matter of a rituals for initiation was also discussed, and a committee was appointed to draw up an outline of an induction ceremony that would be in keeping with the needs of the organization.

Another committee at this conclave was charged with the design and wording of a charter for newly installed chapters, and of a certificate of membership for individual initiates. Finally, the decision reached previously to publish the Sigma Zetan semi-annually was realized during this year.

No conclave was held in 1933; in 1934 the society was again the guest of Otterbein College and Epsilon Chapter. It was at this meeting that the national constitution was adopted. After a discussion of the proposed ritual, the committee was asked to reconcile the different views represented and to continue with the development of a ritual.

It was during this period, for the first time that a chapter of Sigma Zeta became inactive. Eta Chapter found that the competition of special departmental clubs and the lack of active and interested faculty sponsors were handicaps which it could not overcome. However, the chapter was not retired until 1948, after efforts to revive the group had been unsuccessful.

The conclave of 1935 marked the tenth anniversary of the society and appropriately was held at Shurtleff and McKendree Colleges, whose chapters were the two oldest in the organization.

The five years immediately preceding World War II were important ones for Sigma Zeta. The expansion, begun in 1932 with the chartering of Theta Chapter, continued through 1935-1940, six chapters were chartered during this period, making it the most successful five year period in the expansion of the organization.

Interest at Elizabethtown College did not continue and the last member of Theta Chapter was initiated in 1939.

The gradual strengthening of the working structure of the society continued to receive attention of both the national officers and of special committees. The policy of appointing representative committees to study problems in the interim between conclaves and to recommend action to the Executive Council was inaugurated during this period. Committees to deal with publicity, with policies of expansion, with alumni relations, and "to formulate a standard procedure of initiation" were active in these years. Progress along some of these lines was disappointingly slow at times, since most of the work was carried on by correspondence among the committee members located at different chapters.

However, by the time of the sixteenth conclave held at Turkey Run State Park at Marshall, Indiana (1942), substantial progress was reported on each item; the society was listed in Baird's Manual and suitable newspaper and journal coverage had been secured; the proceedings of the conclaves were printed in the Sigma Zetan for the information of chapters and their sponsors; satisfactory alumni relations had been arranged and sanctioned; and even the perennial ritual committee had presented a tentative ritual.

Perhaps the most significant development was the decision to open the conclave program to student papers; this feature has proved an attractive one to the student delegates, and quite possible has done as much as any one other activity to encourage and recognize scholarship among the active members of the various chapters.