With billions of dollars spent on professional development, there remains a very real disconnect between what teachers are given and what they receive especially in terms of the follow-up of an extended PD program. Several theories attempt to explain the differences that exist within the teacher population, but few professional development programs are able to navigate those differences to successfully meet or even identify the needs of all teachers at one time. Constructive-developmental theory proffers that adults vary in their development and some individuals are not at a developmental level to manage some of the complex tasks that are asked of them, i.e., teaching inquiry-based science to middle school students. This study uses the lens of CDT to explore teachers' perception of PD follow-up, their needs of PD follow-up and their thoughts on the viability of a vignette model to identify adult developmental levels as a guide to differentiate PD programs within a case study research design. Modified Subject-Object Interviews were conducted with 12 teachers who participated in a multi-year, inquiry-based professional development probing their perceptions of the effectiveness of various components of the program, what they found most helpful and what support they wish they had. A profile was created of each adult developmental level (termed genres) and vignettes were constructed representing groups of teachers with similar experiences based on those genres. A focus group was conducted to introduce the vignettes and assess their accessibility and functionality in supporting the differentiation of PD programs. The study found that teachers within a focused genre preferred to have examples, resources and experts as support for their development. Teachers in an open genre favored collaboration, guidelines and resources to help them grow. Teachers in the independent genre opted for post-work criticism and interdisciplinary teams along with resources. Lastly, teachers in the reflective genre desired detailed feedback throughout their social learning process. All teachers felt the vignette model was functional and modifications were made to the length and delivery format of the model based on feedback on its accessibility. Findings from this study add to the body of literature on the structure of PD follow-up for extended programs and offers a possible model to support PD differentiation. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]