Homophily-heterophily, staff quality and information literacy as correlates of effective reference services contribute to knowledge especially in librarianship and Information science, it emphasizes on reference services effectiveness which is necessary for graduating high academic quality graduates needed for socioeconomic development.The universities especially in Nigeria or an are expected to train high quality undergraduates needed for socioeconomic development.Non usage and under-utilisation of university libraries because of lack of effective reference services has serious negative implications for the quality of undergraduates,who eventually become graduates that are churned out by the universities in Nigeria.There is serious need for effective reference services in the Nigerian university libraries so that the undergraduates would be attracted to the library.This is because the lecturers within the confines of the classroom cannot do it alone.Non-application of the homophily-heterophily knowledge and skills in reference services transactions, low or poor quality staff, low level of information literacy cannot give effective reference services hence the need for this book.