Not really. We relied on earlier research demonstrating the power of self-selection on voluntary reading and the research on the power of increasing the volume of voluntary reading on reading achievement in the design of our study. Neither of these two variables get much attention in today's research environment but both should be central to any effort to enhance reading achievement. Jimmy Kim has studied the effects of having teachers guide voluntary reading and having parents involved in summer reading and so on but his studies don't show the same effects as ours (he generally gets fewer and smaller effects for giving kids books they we did) but we think his lack of effects is likely due to his selection of the books for the kids rather than allowing them to self-select the books themselves.
We present all this in our new book, Summer Reading: Closing the rich/poor reading achievement gap, published by Teachers College Press.