Magneto‐optic measurements of the tricritical behavior of FeCl2 are presented. These measurements utilize the magnetic circular dichroism of a near infrared absorption of the Fe++ ions in order to determine the total magnetization as a function of temperature and magnetic field near the tricritical point. The resultant description of the magnetic tricritical behavior is consistent with most predictions of a classical Landau analysis, and is found to exhibit a remarkable similarity with the tricritical behavior of 3He‐4He mixtures.