Developmental Test & Evaluation (DT&E) is conducted throughout the acquisition process to assist in engineering design and development and to verify that technical performance specifications have been met. DT&E is planned and monitored by the developing agency and is normally conducted by the contractor. It includes the T&E of components, subsystems, Preplanned Product Improvement (P3I) changes, hardware/software integration, and production qualification testing. It encompasses the use of models, simulations, testbeds, and prototypes or full-scale engineering development models of the system.
Definition: Developmental Test & Evaluation (DT&E) is a test used to compare a system or components against requirements and specifications to reduce risk and inform developers of current performance status.
DT&E provides information to the Program Manager (PM) on the progress of the design process and on the product’s compliance with contractual requirements, effective combat capability, and the ability to achieve key performance parameters (KPPs) and key system attributes (KSAs). The DoD Component’s operational test organization will conduct independent evaluations, operational assessments, or limited user tests to provide initial assessments of operational effectiveness, suitability, survivability, and the ability to satisfy KPPs and KSAs. 
DT&E is focused on early involvement in the acquisition life cycle by testing and evaluating earlier and more effectively, which will help to decrease costs, enhance performance, and retain schedules for programs. (OSD DT&E Website)
Purpose of Developmental Test & Evaluation (DT&E)
The purpose of DT&E is to provide the Program Manager and decision-makers with information to measure a project’s progress, identify problems, examine how a system is going to satisfy key requirements, and manage and reduce risk. DT&E will verify that the system can meet all contractual and technical requirements and is ready to continue development and prepare for Operational Test & Evaluation (OT&E).
Developmental Test & Evaluation (DT&E) Key References
- Main Instruction: DoD Instruction 5000.89 “Test and Evaluation”
- Guide: DAU Test and Evaluation Management Guide – Chapter 7
- Guide: DoD Test and Evaluation Management Guide – Chapter 6
Developmental Test & Evaluation (DT&E) Activities
DT&E includes activities that: 
- Demonstrate that the engineering design and development process is complete
- Demonstrate that the design risks have been minimized
- Demonstrate that the system will meet specifications
- Estimate the system’s military utility when introduced
- Determine whether the engineering design is supportable (practical, maintainable, safe, etc.) for operational use
- Provide test data with which to examine and evaluate trade-offs against specification requirements, life cycle cost, and schedule
- Perform the logistics testing efforts to evaluate the achievement of supportability goals, the adequacy of the support package for the system, (e.g., deliverable maintenance tools, test equipment, technical publications, maintenance instructions, and personnel skills and training requirements, etc.).
Types of Developmental Test & Evaluation (DT&E)
There are three specific types of DT&E which are: 
- Production Acceptance Test & Evaluation (PAT&E): It ensures that production items demonstrate the fulfillment of the requirements and specifications of the procuring contract or agreements.
- Product Qualification Testing (PGT): is also another form of development testing that verifies the design and manufacturing process. PQTs are formal contractual tests that confirm the integrity of the system design over the operational and environmental range in the specification
- Live-Fire Test & Evaluation (LFT&E): is performed by government test representatives and is a tailored type of DT&E for which there is little to no RDT&E-funded development effort. It validates how a system integrates into its intended environment, how it meets specified requirements in accordance with the approved design, and how it meets performance standards.
Conducting Developmental Test & Evaluation (DT&E) 
Execution: The Program Manager will develop detailed test plans for each Developmental Test event identified in the Test and Evaluation Master Plan (TEMP) and provide all required safety documentation to the testers before any test that may be impacted by safety. The PM will conduct test readiness reviews for those events identified in the TEMP.
Evaluation: For ACAT 1B/1C programs on the T&E oversight list for which USD(R&E) did not conduct a DT&E sufficiency assessment, the USD(R&E) will provide the MDA with a program assessment at the development RFP release decision point and MS B and C. This will be updated to support the operational test readiness review or as requested by the MDA or PM. The program assessment will be based on the completed DT&E and any operational T&E activities completed to date, and will address the adequacy of the program planning, the implications of testing results to date, and the risks to successfully meeting the goals of the remaining T&E events in the program
Developmental Test & Evaluation (DT&E) Sufficiency Assessments
The Milestone Decision Authority (MDA) will conduct DT&E sufficiency assessments for Major Defense Acquisition Programs (MDAP) to be included in Milestone B and Milestone C summary reports provided to the congressional defense committees.
Developmental Test & Evaluation (DT&E) Reporting 
- The USD(R&E) and the acquisition chain of command and their designated representatives will have full and prompt access to all ongoing developmental testing and integrated testing, and all DT and integrated test records and reports, including but not limited to: data from all tests, recurring test site status and execution reports, system logs, execution logs, test director notes, certifications, user and operator assessments, and surveys. This applies to all government-accessible data including classified, unclassified, and competition sensitive or proprietary data. Data may be preliminary and identified as such, when applicable.
- The PM and test agencies for all T&E oversight programs will provide DTIC with all reports and the supporting data for the test events in those reports.
- The DoD Components will collect and retain data from DT&E, integrated testing, and OT&E on the reliability and maintainability of ACAT I and II programs.
Developmental Test & Evaluation (DT&E) Lessons Learned
The Program Manager (PM) is responsible for the ultimate success of the overall program. The PM and the test specialists on the PM’s staff must foster an environment that provides the contractor with sufficient latitude to pursue innovative solutions to technical problems and, at the same time, provides the data needed to make rational trade-off decisions between cost, schedule, and performance as the program progresses. 
Difference Between Developmental Test & Evaluation (DT&E) and Operational Test & Evaluation (OT&E)
Where Developmental Test & Evaluation is focused on verifying that technical performance specifications have been met with a system, Operational Test & Evaluation is focused on determining the effectiveness, suitability, and survivability of the weapons, equipment, or munitions for use in combat by typical military users.
AcqLinks and References:
- Defense Acquisition Guidebook (DAG)
-  DAU Test and Evaluation Management Guide – Section 7
-  MIL-HDBK-881 – I.3.3.1 Development Test and Evaluation
-  DoD Instruction 5000.85 “Major Capability Acquisition” – 6 Aug 2020
- DoD Instruction 5000.89 “Test and Evaluation”
- DoD Test and Evaluation Management Guide – Chapter 6
- Air Force Test & Evaluation Guidebook – Dec 2004
- DOT&E and TEMP Guidebook – 28 Mar 13
- Report of the Defense Science Board Task for on Development Test and Evaluation
- Army Regulation 73-1 “Test and Evaluation Policy” – 1 Aug 2006
- Presentation: Introduction to the Developmental Test & Evaluation (DT&E) Process – 2015