Meet The Team

David is licensed in Massachusetts, New Hampshire, Florida, Rhode Island, New York, and New Jersey. He is a member of American Institute of Architects (AIA) and has over 40 years of experience in both residential and commercial design. He is currently the president-elect of Home Builders and Remodelers of Massachusetts and active with the National Association of Home Builders.

With O'Sullivan Architects since 2013, Donnie has been a principal since 2023. Donnie brings an innovative and considerate approach on all  projects.

Erion first worked at O'Sullivan Architects while working on his Architecture degree. He then started his own firm after becoming a member of AIA and has now returned to O'Sullivan Architects as a principal.

Since joining O’Sullivan Architects in 2002, Jonathan has been instrumental in the approval, design, and construction of a broad range of residential and commercial projects. Now an Associate Principal and part owner, he brings a thoughtful and collaborative approach to each phase of the architectural process. Jonathan is known for his ability to interpret traditional forms through a modern lens, creating designs that are both responsive to client needs and grounded in lasting function. He values the freedom to explore ideas and the strong culture of collaboration that defines the OSA team.

Since joining O’Sullivan Architects in 2012, Mark has played a key role in the design and execution of a wide range of commercial projects, including over 20 successful collaborations with colleague Janice Gorman for East Boston Savings Bank. As a Senior Project Manager, he brings a thoughtful, client-focused, and collaborative approach to every project. Mark values the support and creative atmosphere fostered at OSA, especially the way leadership stands behind the team. Outside the office, he finds inspiration riding his bike through the woods or painting in his studio—passions that reflect his creative spirit and dedication. Mark’s deep experience and steady leadership continue to make a lasting impact on the firm’s work and culture.

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With over 12 years of experience in architecture and design, Onelda brings a strong balance of technical expertise and creative vision to her role as Job Captain at O’Sullivan Architects. She is committed to creating spaces where functionality and beauty are seamlessly integrated, guided by the belief that great design has the power to enhance everyday life. Her approach is rooted in thoughtful problem-solving and a collaborative spirit, and she finds the greatest satisfaction in seeing ideas evolve from paper into spaces that feel alive and welcoming. At OSA, Onelda values the teamwork, shared ideas, and the opportunity to contribute to projects with lasting impact. Outside the office, she finds inspiration in nature, time with family, and sketching to spark creativity.

Sara joined O’Sullivan Architects in 2023 and brings a thoughtful, detail-oriented approach to her role as Interior Designer. Since joining the firm, she has contributed to several residential projects, most notably the interiors for 57 Mill Street in Woburn, her largest project to date. Sara enjoys collaborating across disciplines and finds inspiration in the team-oriented culture at OSA, where ideas are welcomed and shared at every level.

Since joining O’Sullivan Architects in 2024, Joseph has brought a focused and reliable presence to the drafting team. Known for his adaptability and attention to detail, he supports a range of residential and multifamily projects, translating design concepts into clear, buildable documentation. Joey thrives in OSA’s collaborative environment, where creative ideas and teamwork drive every project forward.

Isabel joined O’Sullivan Architects in May 2025 and has quickly immersed herself in the early phases of design across several residential projects. She is especially proud of contributing to her first schematic design, which is now progressing into the next stage. With a strong interest in creating spaces that prioritize comfort, function, and the human experience, Isabel values the firm’s thoughtful approach to balancing design integrity with real-world feasibility. Her time at OSA has been shaped by a welcoming, collaborative culture where curiosity is encouraged and learning is part of every day.

Colleen joined O’Sullivan Architects in early 2025 and leads the firm’s marketing operations. With a background in financial services, sports marketing, and hospitality, she brings a strategic and adaptable approach to everything from content planning to client communications. Colleen thrives in OSA’s collaborative environment and appreciates the opportunity to learn something new every day while helping the firm share its story.

Since joining O’Sullivan Architects five months ago, Rita has been essential to keeping the office running efficiently, ensuring the team can focus on their creative work. As Office Manager, she brings an organized, adaptable, and calm approach to every task, supporting projects and processes behind the scenes. Rita values the friendly, collaborative culture at OSA and takes pride in helping the team operate smoothly, while also finding time to pursue her own adventures, like climbing Half Dome in Yosemite Park.