We report in this paper, measurements of the nonlinear susceptibility χ 3 (T) in the metamagnetic heavy fermion (HF) compound UPt 3 . At high temperatures, χ 3 (T) < 0 and small. It turns positive for T ≤ 35K, forms a peak at T 10K and then decreases to zero with further decreasing temperature. The peak in χ 3 occurs at a temperature T 3 roughly half of T 1 , the temperature of the maximum in the linear susceptibility. We present results on URu 2 Si 2 and UPd 2 Al 3 to show that this feature is common to other HF materials. A two level model to describe the metamagnetic transition, with separation between the levels being the only energy scale, captures all experimentally observed features. *bss2d@virginia.edu -to whom all correspondence should be addressed.2 Given the myriad ways in which one can arrange atoms to form crystal structures and the possibilities of placing electrons in them the discovery of a common behavioral pattern in the electronic properties often leads to new microscopic insights. In metals, recent discoveries of universal rules such as the Kadowaki-Woods relation 1 which connects the electron effective mass enhancement to the temperature dependence of the resistivity in Fermi liquid systems, the constancy of the Wilson ratio 2 , the Homes plot 3 and other similar scaling laws have assisted in identifying the dominant energy scales, and helped in insights to build microscopic theories.Our purpose in this paper is to show that the magnetic response of many electronic materials that undergo a metamagnetic transition also exhibit universal features in their nonlinear susceptibility. Along with a jump in the magnetization at a critical field, H m , metamagnetism also entails a positive nonlinear susceptibility at low temperatures (it is negative at high temperatures), a peak in the linear susceptibility 1 (T) at a temperature T 1 , a peak in the leading order nonlinear susceptibility 3 (T) >0 at a lower temperature T 3 . These are features widely seen in different materials with diverse lattice structures and electronic properties. Hirose et. al 4 have noted the correlation between H m and the temperature T 1 of the maximum in 1 (T). Goto et. al pointed out earlier that the metamagnetic field H m also correlates with the value of 1 (T) at its maximum 5 . Both of these correlations, found in a number of materials, indicate a dominant presence of one energy scale. In the following we report a new correlation, one between the peak temperatures T 3 for 3 (T) and T 1 namely T 3 =T 1 /2. We also present a new model that captures all of these correlations.For purposes of illustrating this universality we consider the heavy electron class of materials. Within these systems metamagnetic behavior is seen in several uranium compounds 6,7,8,9,10 , cerium compounds 11,12,13,14 , as well as in the ytterbium compounds 15 . Most of these systems possess either hexagonal or tetragonal symmetry. The same behavior is also observed in the skutterudite structure in PrOs 4 Sb 12 a moderately heavy...