The purpose of this study was to evaluate the thesis that matching locus of control with type of relaxation training enhances physiological self-control. This was accomplished by comparing the effectiveness of a somatic and a cognitive relaxation method for internal and external locus of control subjects. It was hypothesized that the two techniques vary in degree of cue salience, and that the attentional strategy of internals would interact with the cognitive approach while externals would respond better to the somatic approach. Subjects were 80 volunteers from stressful occupations who scored high on the State-Trait Anxiety Inventory A-trait scale. Forty internals and 40 externals as defined by extreme scores on the Adult Form Nowicki Strickland Locus of Control Scale were randomly assigned to either the Jacobson or Autogenic group for five weekly laboratory training sessions with daily home practice. The effectiveness of the relaxation training was measured by six dependent variables: EMG, skin temperature, heart rate, State-Trait Anxiety Inventory (A-state and A-trait scales), and self-reported home practice sessions. The data were analyzed by using analyses of variance with repeated measures. The expected interaction between locus of control and type of relaxation training was found only for heart rate. While the treatment was effective in reducing physiological and subjective anxiety for all subjects, internal locus of control subjects and those who received Jacobson training reduced muscle tension and increased temperature better than externals and subjects in the Autogenic group. Externals became more internal during training, and the allegedly stable characteristic of trait anxiety significantly decreased. The possibility that heart rate may be a less easily perceived parameter than EMG or skin temperature is discussed, and it is recommended that future research evaluate other physiological variables for enhanced responsivity under congruent conditions. The importance of further basic research on relaxation training is emphasized, and it is noted other aspects of this widely used treatment approach should be investigated for interactions with locus of control.