Somerville Planning Board Adopts Ballantyne Administration’s Transformative Assembly Square Neighborhood Plan

By unanimous vote, the Somerville Planning Board at their July meeting adopted the Ballantyne Administration’s Assembly Square Neighborhood Plan, marking a significant milestone in the City's efforts to guide sustainable development in one of its most rapidly evolving neighborhoods. Once fully implemented, the neighborhood plan offers the potential of up to 2,900 to 5,700 new residential units -- including roughly 580 to 1,100 affordable units -- and an estimated up to $17 million in annual tax revenues among other community benefits.  

"This plan represents a pivotal moment for our community," said Mayor Katjana Ballantyne. "Assembly Square has incredible potential to become a model for inclusive, sustainable development that serves both our residents and the broader region. By adopting this shared vision for a thriving, equitable Somerville, we are creating a path to adding much-needed housing including affordable units, new jobs, more access to nature, and to generating vital tax revenues to help fund our community’s needs and priorities.”  

The plan is the result of years of collaborative work by residents, stakeholders, and City leadership and staff to establish a long-term vision for Assembly Square's future. It serves as both a master plan and will become a zoning recommendation that will shape development decisions in the approximately 140-acre East Somerville site along the Mystic River.  

The neighborhood, formerly an industrial site, now includes the successful Assembly Row mixed-use complex featuring offices, shopping, and housing alongside longer-standing retail and light industrial spaces. That transformation is the successful result of intensive community-shaped discussions and goal setting as well that began in the late 1990s. More recently, Assembly was designated a Transformational Area in SomerVision2040, the City’s comprehensive plan, with significant potential for growth. 

The new plan emphasizes realizing Assembly Square's full promise as a major regional destination, job engine, revenue creator, and housing generator. The plan also addresses critical infrastructure needs to support expected growth while ensuring development aligns with community values and long-term sustainability goals. 

The planning process included extensive community engagement through community meetings, public presentations, polls and surveys, and feedback sessions that spanned several years. The Planning Board reviewed multiple drafts before adopting the final version, which incorporates revisions based on public input and technical analysis. 

Key elements of the adopted plan include: 

• Framework for walkable mixed-use development that balances residential (approximately 40% of built area), and commercial (around 60%) uses to create a complete community
• Provisions for affordable housing integration throughout the neighborhood at 20% of the total new units (equaling roughly 580 to more than 1,000 affordable units)  
• Significant opportunities for growing large, small, and micro businesses to strengthen the community’s job and tax base and neighborhood vibrancy
• Guidelines for sustainable development practices and climate resilience
• Strategies for preserving and enhancing public spaces, such as Baxter Park, and creating community amenities on approximately 28 acres totaling roughly 20% of the land
• Infrastructure improvements to support population growth, mobility and transit access, and connectivity
• A roadmap for coordinated improvements that will benefit both new and existing residents. 

The plan builds on Assembly Square's existing assets, including its proximity to public transportation via the MBTA Assembly Orange Line station and its growing business cluster, while addressing challenges related to traffic, infrastructure capacity, and community services.  

“It’s great to have a new neighborhood plan in place that acknowledges the changes in development and economics since the first plan in 2000 and the master plan from 2004. This was a fun process and involved so many engaged and truly caring neighborhood residents that we’re excited to facilitate the future growth and amenities for them,” said Senior Planner and project lead Sarah Lewis. 

Community members can access the full adopted plan and related documents through the city's SomerVoice platform at voice.somervillema.gov/assemblynp. 

The Ballantyne administration is committed to creating inclusive, sustainable communities that serve residents across all neighborhoods. For more information about city planning initiatives, visit voice.somervillema.gov.

Accessibility 

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