During the fall of the 2016-17 school year, first, second, and third grade students in six elementary schools -- two in St. Paul and Eagan, Minnesota, and four in Bedford County in the Piedmont region of Virginia -- were assigned to take part in randomized efficacy trials carried out for the purpose of rigorously evaluating the impact of "Tutoring with the Lightning Squad" on reading outcomes. The study was designed to follow procedures that could qualify for "meets standards without reservation" in the What Works Clearinghouse (Standards 3.0). "Tutoring with the Lightning Squad" showed a significant and substantial impact on Woodcock measures of Passage Comprehension and Word Attack for students who received at least 25 sessions of tutoring. No significant differences were seen for Letter-Word Identification -- a result which can be attributed, at least in part, to the fact that this skill is specifically addressed only in the earliest levels of the program. Results did not vary for students by grade, gender, or ethnicity. In summary, this efficacy study suggests that "Tutoring with the Lightning Squad" has the potential to provide schools with a cost-effective tool for increasing reading levels, as the impacts of our program among students in small groups supervised by a paraprofessional tutor compare favorably with the much more expensive one-to-one tutoring models considered the most effective intervention for struggling readers.