History is replete with overt discrimination on the basis of race, gender, age, citizenship, ethnicity, marital status, academic performance, health status, volume of market transactions, religion, sexual orientation, etc. However, these forms of discrimination are not equally tolerable. For example, discrimination based on immutable or prohibitively unalterable characteristics such as race, gender, or ethnicity is much less acceptable. Why? I develop a simple rent-seeking model of conflict which is driven by either racial (gender or ethnic) discrimination or generational discrimination (i.e., young versus old). When the conflicts are mutually exclusive, I find that racial discrimination is socially intolerable for a much wider range of parameter values relative to generational discrimination. When they are not mutually exclusive, I find that racial discrimination can be socially intolerable while generational discrimination is socially tolerable. The converse is not true. My results are not driven by a stronger intrinsic aversion to discrimination on the basis of immutable characteristics. I am able to explain why some forms of discrimination (e.g., racism) are much less tolerable than other forms of discrimination (e.g., age discrimination) without making any value judgements about either form of discrimination.