The Web has transformed our lives, and a cursory review of recent headlines shows both our dreams and nightmares writ large as a result. Is it possible to retain the benefits through algorithms and apps for romance, books, music, and fitness, without suffering the devastation wrought by the hacking of health records, elections, and bank accounts? This special issue explores the many facets of Web Science, the study of the Web’s impact on our society and technology, and how we can use it to achieve our dreams without living our nightmares.