Substantial research has been devoted in recent years to the development of a new and alternative test methodology to the standard explicit questionnaire (De Houwer, 2006). This current research was concerned with the laboratory development of one alternative methodology known as the Function Acquisition Speed Test (FAST; O'Reilly, Roche, Ruiz, Tyndall, & Gavin, 2012), into a functionally understood assessment of homonegativity, or anti-gay bias. In brief, the FAST was built around the idea that the stronger a pre-existing relation is between two classes of stimuli (e.g., Gay-Bad), the more resistance will be encountered when learning to form a new functional response class that is in opposition to it (e.g., Gay-Good). This current research programme has focused primarily on establishing the optimal stimulus set for a Homonegativity FAST. Specifically, Experiments 1 and 2 utilised a knowngroups approach to compare and contrast the relative effectiveness of semantically representative verbal and pictorial exemplars in a "single-phase" Gay-Good FAST. Experiments 3a and 3b investigated the suitability of more emotive pictorial stimuli high in affective valence in a "two phase" FAST, assessing the resistance to the formation of a Gay- Good class relative to neutral or contrasting functional stimulus classes. Together, the findings from this research suggest that affective pictorial stimuli are the most suitable exemplars in a FAST for homonegative prejudice. Additionally, this research highlighted the enhanced stability of a "two-phase" FAST examining Gay-Good and Gay- Bad verbal histories simultaneously for providing a more accurate and conceptually valid assessment of homonegativity. Thus, over the course of this research, the FAST has been refined and developed into a functionally understood prototype for the assessment of homonegativity. More specifically, this research has identified an effective and representative stimulus set, in addition to establishing a valid and stable tw0-phase FAST format capable of ascertaining an individual's homonegative verbal histories.