1. **State the problem:** Calculate $\frac{1}{5} - \frac{3}{5}$. 2. **Formula and rules:** To subtract fractions with the same denominator, subtract the numerators and keep the denominator the same. 3. **Intermediate work:** $$\frac{1}{5} - \frac{3}{5} = \frac{1 - 3}{5} = \frac{-2}{5}$$ 4. **Explanation:** Since the denominators are equal, we subtract the numerators directly. The result is a negative fraction because $1$ is less than $3$. 5. **Final answer:** $$\boxed{-\frac{2}{5}}$$