In the late 1960s and early 1970s, fraternity membership began to decline all around the United States, a trend which did not spare Phi Mu Delta. They had begun to prosper in the 1960s and even opened their first National Headquarters in Lancaster, Pennsylvania. There was a complete professional staff and traveling consultant. However, with the declining membership, it was getting harder and harder to maintain the office. While several new chapters were started in the 1970s, they all died due to a lack of support and membership.
In 1974, another small, financially strapped national, Delta Phi, approached Phi Mu Delta about a merger. Plans were made and both organizations planned to merge under the name, Delta Phi. However, Phi Mu Delta’s crest and colors would be retained. All started well, but due to an impeding lawsuit against Delta Phi, the merger was called off. Instead, a new innovative plan was established. Phi Mu Delta and Delta Phi would remain separate organizations, but share a National Office and pool other resources. In fact, this plan looked so successful, that another small, national organization, Alpha Delta Gamma, entered into the deal. This deal also had its problems when one of the organizations could no longer afford their percentage of the agreement. Phi Mu Delta was on its own again.
In the late 1970s, it appeared that Phi Mu Delta would dissolve. Many alumni and undergraduate members were actually calling for such an action. The chapter at MIT left in 1977 and has continued to exist as a local, Nu Delta, to this very day. However, a group of very young new alumni, led by the more experienced alumnus, Eli Henry, began to rebuild the organization. A new National Office was established in State College, Pennsylvania, when they hired Stewart Howe Alumni Service to run their daily affairs. The Triangle began to be published again and the chapter at the University of Vermont was reestablished.
The 1980s began as a time of rebuilding. Phi Mu Delta rewrote its constitution, re-established the Phi Mu Delta Foundation and began to invest much time in its remaining chapters. The only new chapter of this period was established at California University of Pennsylvania. The Mu Pi Chapter was once a part of the Theta Delta Chi fraternity. However, in 1979 the Pi Triton local fraternity separated from Theta Delta Chi and petitioned Phi Mu Delta in 1985.
The 1990s were a great time of growth for Phi Mu Delta. Their chapters were extremely strong and active in their communities. The Nu Beta Chapter at the University of New Hampshire had closed its doors in 1981. In the spring of 1995, the chapter was re-activated and has helped renew PMD’s interest in expansion efforts. Indiana University of Pennsylvania, Mansfield University of Pennsylvania and Lycoming College were added to the fraternity in the late 1990s. In April of 1999, Mu Pi chapter was closed for an inability to maintain viable chapter operations.