Cook the pasta according to the package directions. Reserve 1/2 cup of the cooking water, drain the pasta, and set aside. Wipe out the pot.
Heat the oil in the pasta pot over medium heat. Add the bell peppers and garlic and cook, stirring occasionally, until the peppers are tender, 5 to 7 minutes.
Add the arugula, bocconcini, the cooked pasta, the reserved pasta water, 1 1/4 teaspoons salt, and 1/4 teaspoon pepper. Cook, stirring, until the arugula is just wilted, about 1 minute.
CALORIES 684(40% from fat); FAT 30g (sat 12g); CHOLESTEROL 39mg; CARBOHYDRATE 72g; SODIUM 1235mg; PROTEIN 36g; FIBER 4g; SUGAR 6g