jmc

There are 6 equally likely outcomes for each die, so there are $6\times 6=36$ total equally likely outcomes for both dice together. The outcomes which sum to 7 are: 1 + 6, 2 + 5, 3 + 4, 4 + 3, 5 + 2, and 6 + 1, for a total of 6 equally likely successful outcomes. Therefore, the probability of rolling a sum of 7 is $\frac{6}{36}=\boxed{\frac{1}{6}}$.