Email updates

Keep up to date with the latest news and content from Implementation Science and BioMed Central.

Journal App

google play app store
Open Access Open Badges Research

Developing program theory for purveyor programs

Christa Oosthuizen* and Johann Louw

Author Affiliations

Department of Psychology, University of Cape Town, PD Hahn Psychology Building, (Chemistry Mall), University Avenue, Cape Town, South Africa

For all author emails, please log on.

Implementation Science 2013, 8:23  doi:10.1186/1748-5908-8-23

Published: 19 February 2013



Frequently, social interventions produce less for the intended beneficiaries than was initially planned. One possible reason is that ideas embodied in interventions are not self-executing and require careful and systematic translation to put into practice. The capacity of implementers to deliver interventions is thus paramount. Purveyor organizations provide external support to implementers to develop that capacity and to encourage high-fidelity implementation behavior. Literature on the theory underlying this type of program is not plentiful. Research shows that detailed, explicit, and agreed-upon program theory contributes to and encourages high-fidelity implementation behavior. The process of developing and depicting program theory is flexible and leaves the researcher with what might be seen as an overwhelming number of options.


This study was designed to develop and depict the program theory underlying the support services delivered by a South African purveyor. The purveyor supports seventeen local organizations in delivering a peer education program to young people as an HIV/AIDS prevention intervention. Purposive sampling was employed to identify and select study participants. An iterative process that involved site visits, a desktop review of program documentation, one-on-one unstructured interviews, and a subsequent verification process, was used to develop a comprehensive program logic model.


The study resulted in a formalized logic model of how the specific purveyor is supposed to function; that model was accepted by all study participants.


The study serves as an example of how program theory of a ‘real life’ program can be developed and depicted. It highlights the strengths and weakness of this evaluation approach, and provides direction and recommendations for future research on programs that employ the purveyor method to disseminate interventions.

Program theory; Logic models; Purveyor; Dissemination; Implementation fidelity