Based on
https://en.wikipedia.org/wiki/Dartmo..._organizations
Only groups which have left a National at one point are included.
Fraternities
Alpha Delta (Once part of Alpha Delta Phi)
Alpha Chi Alpha (Twice part of Alpha Chi Rho)
Dartmouth Beta (Once part of Beta Theta Pi)
Bones Gate (once part of Delta Tau Delta)
Gamma Delta Chi (from both Alpha Chi Rho and Phi Kappa Sigma)
Sigma Phi Epsilon (Disassociated from Sigma Phi Epsilon and then reaffiliated)
Sigma Nu (Disassociated from Sigma Nu and then reaffiliated)
Phi Delta Alpha (once part of Phi Delta Theta)
Chi Gamma Epsilon (once part of Kappa Sigma)
Chi Heorot (once part of Chi Phi)
Sororities
Epsilon Kappa Theta (once part of Kappa Alpha Theta)
Sigma Delta (once part of Sigma Kappa)
Coeducational
Alpha Theta (once part of Theta Chi)
The Tabard (once part of Sigma Chi)
Phi Tau (once part of Phi Sigma Kappa)
Defunct
Foley House (once part of Delta Upsilon)
Pi Sigma Psi (once part of Delta Phi Epsilon )
Harold Parmington Foundation/Delta Psi Delta (once part of Tau Epsilon Phi)
Zeta Beta Chi (once part of Delta Gamma)
Xi Kappa Chi (once part of Alpha Chi Omega, under consideration for affiliation with Phi Mu)
Phoenix (once part of Phi Gamma Delta)
Panarchy (once was part of Phi Kappa Psi)
Reasons for disaffiliation range widely from unwillingness to exclude negro members to low membership to unwillingness of the National Fraternity to help with loans for fixing the house.