To find the sum of \( p \) and \( q \), where \( p = \frac{2}{3} \) and \( q = -\frac{5}{3} \), we calculate:
\[ p + q = \frac{2}{3} + \left(-\frac{5}{3}\right) = \frac{2}{3} - \frac{5}{3} \]
Since the denominators are the same, we can subtract the numerators directly:
\[ p + q = \frac{2 - 5}{3} = \frac{-3}{3} \]
Now, simplifying \( \frac{-3}{3} \):
\[ \frac{-3}{3} = -1 \]
Thus, the sum of \( p \) and \( q \) is \( -1 \).
Therefore, the answer is \(\boxed{-1}\).