The area of judicial research previously referred to as the freshman effect has generated a substantial amount of interest among Supreme Court scholars. Until recently, however, efforts to establish the existence of this effect have met with mixed success. Hagle (1993a) contends that the mixed results of previous freshman or acclimation effect studies are primarily due to the use of the behavior of the experienced justices as a baseline to measure the behavior of the new justice. Given normal variations in the justices' behavior, using the behavior of experienced justices to determine whether a new justice experienced acclimation effects may lead to a false conclusion. In this study we examine the opinion writing behavior of 24 justices who joined the Court from the 1943 through the 1993 Terms. While controlling for the number of cases, we use each justice's own later opinion writing behavior in each of two control periods as a baseline against which to judge whether that justice experienced an acclimation effect in his or her first-term opinion writing. We also compare the opinion writing behavior of Rehnquist and the other three Chief Justices with that of the Associate Justices. Our results indicate that a substantial number of the justices (67%) manifest significant acclimation effects in their opinion writing for one or both of the two control periods. Our results also show a significant difference in Rehnquist's opinion writing behavior as he moved from Associate Justice to Chief Justice and a substantial difference between the opinion writing behavior of the Chief Justices as compared to the Associate Justices.