One-third of the students who attend Grant School are taking Algebra. One-quarter of the students taking Algebra are also on the track team. There are $15$ students on the track team who take Algebra. Find the number of students who attend Grant School.
1. Let \( S \) be the total number of students who attend Grant School.
2. According to the problem, one-third of the students are taking Algebra. Therefore, the number of students taking Algebra is:
   \[
   \frac{S}{3}
   \]
3. One-quarter of the students taking Algebra are also on the track team. Therefore, the number of students on the track team who take Algebra is:
   \[
   \frac{1}{4} \times \frac{S}{3} = \frac{S}{12}
   \]
4. We are given that there are 15 students on the track team who take Algebra. Therefore, we can set up the equation:
   \[
   \frac{S}{12} = 15
   \]
5. To find \( S \), we solve the equation:
   \[
   S = 15 \times 12 = 180
   \]

The final answer is \( \boxed{180} \)