About us
Built on Vision, Evolved Through Growth
Empower, Educate, Elevate.
In December 2024, Theresha Diallo acquired majority ownership of The Onyx Group of Alexandria, uniting its 40+ year legacy and federal past performance with the vision and leadership of The Diallo Group. Following the acquisition, the firm was rebranded and consolidated under a single name “The Diallo Group” bringing together combined expertise, resources, and capabilities into one strengthened organization. This strategic merger reinforced our depth in federal planning and design while positioning the firm for continued national growth.
Founded in 1983, the firm has built a long-standing reputation for delivering innovative planning and design solutions, primarily within the federal sector, with a strong emphasis on military installation and facilities planning. For more than four decades, we have supported mission readiness, infrastructure modernization, and long-term asset management through strategic, sustainable, and integrated planning approaches.
While our foundation remains rooted in federal work, our portfolio has expanded to include select commercial and local engagements. Recent projects include collaborations with nationally recognized brands such as Disney, local commercial partnerships including ABC Fine Wine & Spirits, and residential design projects throughout the Orlando region. This diversification reflects our ability to apply federal-level discipline, rigor, and strategic thinking across multiple sectors.
Our multidisciplinary team of planners, architects, designers, landscape architects, interior designers, and GIS specialists works collaboratively to deliver comprehensive land and facilities lifecycle solutions. By integrating planning, architecture, technology, and design, we create environments that are functional, resilient, and forward-looking.
At The Diallo Group, our work is guided by our core belief: Empower. Educate. Elevate. We empower organizations through strategic insight, educate stakeholders through data-driven planning, and elevate communities through thoughtful, impactful design.
Empower
We empower our clients, team members, and communities by providing tools, knowledge, and solutions that drive success and foster independence.
Education
We are committed to sharing knowledge, promoting learning, and creating opportunities for growth through collaboration and innovation.
Elevate
We strive to elevate standards, ideas, and outcomes by delivering exceptional solutions that inspire progress and make a lasting impact.
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Why Choose Us
Trusted Experts in Design & Planning
TDG specializes in providing architecture and engineering services to federal customers worldwide. Over our 40 years in business, we have offered comprehensive planning, architecture, interior design, landscape architecture, and technology solutions to agencies such as the DOD, DHS, DOT, DOE, DOl, and GSA.Our Experties in environmental consulting and sustanability complements TDG extensive suite of archietecture and engineering services.
We are dedicated to excellence in project management across all scales, consistently meeting and exceeding client expectations.
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Our Journey
Built on Legacy. Driven by Vision.
Over four decades ago, The Diallo Group was founded with a vision to deliver innovative, mission-driven solutions in engineering, planning, and federal facility support. What began as a small team of technical experts has evolved into a nationally recognized firm trusted by the Department of Defense and other federal agencies.
