Bradford Skow's elegant and tightly argued book goes very much against the prevailing tide of recent discussions of scientific explanation. While many emphasize the pluralism and contextualism of explanatory practice, Skow offers a remarkably simple account of explanation for events: the reasons why an event occurs are always either causes or grounds of that event. Skow's defense of this account is ingenious and worth taking seriously...Skow offers an innovative and refreshing intervention in debates about explanation and reasons why. His approach will surely be of interest to those sympathetic to Lewis' work on explanation and to those with a stake in integrating causes and grounds into a coherent metaphysical picture.