 He worked with Karl Pearson and Raphael Weldon in the Association for Promoting a Professorial University for London.Foster was a leading light in the movement to reconstruct University College into a University of London which taught and examined, and throughout the 1880s and 1890s he campaigned to unify its teaching and examining functions, a sensitive debate, his tact being indicated by his appointment as the first Principal of University College in 1900 upon his retirement from teaching.In his four-year tenure he oversaw considerable reorganisation and development of the college, substantially increasing the provision of accommodation, and cultivating growth in its intellectual and social activities.