Collaborative teaming among specialists can enhance educational success by leveraging resources and building capacity to maximize effectiveness. Special educators' change in perceptions of their efficacy as collaborators in the education of students with autism spectrum disorder (ASD) was studied before and after completing a year-long federally funded graduate certificate program in autism. Self-perceptions of collaborative expertise were examined in eight cohorts of educators over 7 years. Analysis of the results indicated a significant increase in perceptions of efficacy level in six of the cohorts at = 0.006. The size of the effect of the program on participants' self-perceptions of their efficacy in working collaboratively with other school personnel was large for seven of the cohorts and medium for one. Most importantly, results from Greenhouse-Geisser analysis showed that the posttest scores on collaboration efficacy level were significantly higher than the pretest scores across all cohorts, and that the pattern of change in pretest to posttest scores was similar across all eight cohorts.