To solve the expression \( 17 - (-18) \), we need to remember that subtracting a negative number is equivalent to adding the positive version of that number.
So, we have:
\[ 17 - (-18) = 17 + 18 \]
Now, we can perform the addition:
\[ 17 + 18 = 35 \]
Therefore, the answer is \( 35 \).