Music composed by computers has always been lacking in "musical" qualities: mood, emotional expression, and a sense of purpose or goal. A musical expert system called EMOTER is the first attempt to address these important musical aspects. EMOTER receives as input a list of moods (e.g., happy, lively) and generates melodic passages intended to evoke those moods in an organized, coherent fashion. EMOTER composes the basic units of music called phrases. Results with EMOTER are excellent. Some of the musical phrases generated from a mood-specification are comparable to music that a reasonably talented composer might produce. More theory is needed, however, before the full complexities of human-composed music are sufficiently captured in code for EMOTER to pass a Turing test in music composition.