On January 1, 2007, we lost a cherished friend, colleague and mentor. Jeffrey Jack developed an early interest in aquatic organisms and at Wake Forest University devoted his initial graduate research with Ron Dimock to the study of freshwater mussels and mites. He later earned his Doctorate with John Gilbert at Dartmouth College by examining the population dynamics between zooplankton and protists. Jeff’s post-doctoral research drew him to large rivers where he investigated the effects of predation on zooplankton communities. Early last year, Jeff rose to the position of Tom Wallace Chair in Conservation Biology at the University of Louisville because of his important contributions to improving the quality of aquatic habitats in Kentucky. His many contributions include developing functional bioassessments for stream restorations, expanding our knowledge of urban effects on streams and springs, improving freshwater mussel conservation and determining the impacts of mountaintop removal coal-mining on headwater streams. Jeff leaves a legacy of humor, humility, professionalism, devotion to family and faith. Presented here is a synopsis of his work and a collection of memories of Jeff from his students, colleagues and friends. Jeff will be dearly missed by all who knew and learned from him.