In the present thesis a literature review revealed that further investigation is required into cases where clinical fears and anxiety exist but cannot be traced to a specific conditioning event in a person’s life. The processes of stimulus equivalence, derived relational responding and the derived transfer of functions effect in particular, were identified as having significant potential for the explanation of such “unconditioned” clinical anxiety. Whilst early studies dealt with anxiety as mere avoidance, this idea was eventually challenged. It was since proposed that avoidance only becomes problematic when it eliminates contact with appetitive events and/or puts the individual in contact with aversive events. In other words, avoidance is problematic when conflicting contingencies supporting one or both of these consequences are present. The current research aimed to generate a procedure to investigate precisely this conflicting contingency phenomenon, i.e., approachavoidance conflicts in the laboratory through eight computer-based experiments. The procedures presented in Chapter 2 (Experiments 1, 2 and 3) outlined three experiments that attempted to generate conflicting approach contingencies through derived relations, produced response variability across participants and reaction time delays within participants and provided a means with which to analyse more ecologically valid approach-avoidance conflicts. Chapter 3 outlined two experiments (Experiments 4 and 5) which attempted to generate response disruption similar to that reported in Chapter 2, using competing approach and avoidance contingencies in place of competing approach contingencies. Response variability across, but not typically within, participants was observed during both experiments and delayed reaction times were observed during Experiment 5. The two experiments outlined in Chapter 4 (Experiments 6 and 7) produced approach-avoidance conflicts using mild electric shocks and small amounts of money during which conflicts were generated with greater appetitive and aversive salience than those presented during previous experiments. As reported during previous chapters, response variability was observed across participants but not typically within and reaction time delays were produced during conflict trials. Self-report anxiety ratings revealed greater anxiety during conflict than non-conflict trials during Experiment 6 but not 7. The experiment presented during Chapter 5 (Experiment 8) aimed to address the issue of response consistency observed within-participants during previous experiments by varying the amount of money on offer during approach-avoidance conflicts on a trial-by-trial basis. Again, response variability across, but not within participants, was observed. Skin resistance responses did not reveal higher rates of arousal during conflict trials than non-conflict trials and the findings are covered in detail. Finally, Chapter 6 provides a summary of the entire research programme presented in this thesis, and reviews the development of a procedure to generate laboratory-based approachavoidance conflicts by derived stimulus relations. The relationship of the current research to the relevant literature, future research suggestions and clinical implications are discussed.