This introductory article addresses the question,'Are the Multidimensional Health Locus of Control (MHLC) scales valid?' The initial evidence for the validity of the family of MHLC scales is reviewed, followed by a discussion of the empirical evidence for the hypothesis linking MHLC scale scores to measures of health behavior. There is ample evidence in the literature that the MHLC scales validly assess health locus of control beliefs. Nevertheless, caution should be used when making generalizations regarding the validity of the MHLC scales to new theoretical or situational contexts. The theoretical relationships between these beliefs and other constructs are complex, making it necessary to thoughtfully consider the valid application of the MHLC scales in each new study.