Director, HR Business Partner

Reflection is a research lab making intelligence open and accessible for everyone to use, customize, and build on. We build open models that let anyone control their intelligence and help shape the future of AI. Our mission: make intelligence open and accessible to all.

About the role

We're looking for a tenured HR Business Partner to serve as a strategic advisor to functional leaders across our technical and non-technical teams. This is a foundational role with real scope: you'll help build the HRBP function from the ground up, establishing the management infrastructure, people frameworks, and organizational discipline that will carry us through our next stage of growth.

You bring experience leading HR teams and know what it takes to build a function — not just support one. You'll work closely with senior and executive leaders to strengthen team performance, sharpen org design, and navigate the complex people decisions that come with scaling. This role sits at the intersection of strategy and execution, and the person we're looking for knows how to operate credibly in both.

What you'll do

• Lead and develop a team of HR professionals, setting a high bar for quality, consistency, and business partnership across the function

• Serve as a trusted advisor to senior and executive-level leaders, providing credible counsel on organizational design, team structure, and workforce planning

• Drive the build-out of the HRBP function — defining how the team operates, where it adds value, and how it scales alongside the business

• Coach leaders through high-stakes people decisions — performance management, calibrations, promotions, and complex separations — with consistency and sound judgment

• Build and own scalable people frameworks, from management toolkits to performance improvement practices, that hold up as the organization grows

• Guide leaders through change, scaling challenges, and periods of organizational ambiguity

• Act as a bridge between business leaders and the broader People team, translating strategy into action and ensuring alignment across functions

• Support talent planning, succession conversations, and flight risk assessment across key functions

What you bring

• 10+ years in HR, with experience in a senior HRBP role and a track record of leading and developing HR teams

• Experience building or scaling an HRBP function, including defining team structure, operating model, and ways of working

• A proven ability to influence and advise at the executive level, with the credibility and judgment to push back when it matters

• Strong experience managing complex employee relations matters and workplace investigations

• Demonstrated ability to build HR frameworks and people infrastructure in high-growth or technology environments

• Deep working knowledge of US employment practices; UK exposure is a plus

• The ability to operate effectively in ambiguity — balancing strategic thinking with a willingness to roll up your sleeves

• A reputation for fairness, consistency, and keeping the employee experience at the center of every decision

We believe that to make intelligence open and accessible to all, you need to start at the foundation. Joining Reflection means building from the ground up as part of a talent-dense team. You will help define our future as a company, and help define the future of open foundational models.

We want you to do the most impactful work of your career with the confidence that you and the people you care about most are supported.

• Top-tier compensation: Salary and equity structured to recognize and retain our talent globally.

• Stock options: Everyone who joins and contributes to Reflection's success gets to share in the upside through stock options.

• Health & wellness: Comprehensive medical, dental, vision, and life, with an annual wellness allowance.

• Meals: Lunch and dinner are provided in the office daily.

• Life & family: 22 weeks paid parental leave for all new birthing and non-birthing parents, including adoptive and surrogate journeys.

• Vacation days: Unlimited paid time off in the U.S. and 30 days in the U.K.

• Sponsorship support: We sponsor visas to help exceptional talent join our team and support long-term immigration pathways where applicable.

• Team building: We have regular off-sites, happy hours, and team celebrations.