Rationalization may refer to:
- Rationalization (sociology), the means of transition from a traditional society into a rationalized one
- Rationalization (economics), an attempt to change a pre-existing ad-hoc workflow into one that is based on a set of published rules. Also, business jargon for a reduction in numbers
- Rationalisation (mathematics), the process of removing a square root or imaginary number from the denominator of a fraction
- Rationalization (making excuses), a psychological defense mechanism in which perceived controversial behaviors are logically justified
- Post-purchase rationalization