A study was conducted to determine if actual California Achievement Test subtest scores were significantly different than expected in a large, urban school district that had just implemented its first component--staff development--based on the Effective School Model (ESM). Subjects consisted of 1,591 fourth through sixth graders and 1,557 sixth through eighth graders who had been grouped according to subgroup characteristics. Regression was used to obtain predicted scores and a dependent t test was applied to compare the actual and predicted means. For sixth and eighth graders, overall achievement was at or above the expectancy level for most subgroups. Average actual reading scores for sixth graders were significantly higher than expected; however, sixth-grade students from upper socioeconomic groups fell significantly below expectations for reading and language. For eighth graders, actual average reading and mathematics scores were significantly below expected. Findings suggest that educational administrators should: (1) continue to implement the components of the ESM, initiating measurement of student success immediately and focusing on high-risk students; and (2) attend to long-term, rather than short-term, trends. Two data tables are included. (Author/TJH)