To apply the property of negative integer exponents, we use the rule that \( a^{-n} = \frac{1}{a^n} \).
Using this rule for \( 7^{-2} \):
\[ 7^{-2} = \frac{1}{7^2} \]
Next, we need to calculate \( 7^2 \):
\[ 7^2 = 49 \]
Thus, we have:
\[ 7^{-2} = \frac{1}{49} \]
Therefore, the answer is:
\[ 7^{-2} = \frac{1}{49} \]