Interim HR Manager

Flagship Pioneering•Cambridge, MA

2d•Onsite

About The Position

Flagship Pioneering is seeking an Interim HR Manager to provide full-cycle HR support across multiple early-stage life sciences portfolio companies during a planned leave of absence. The role serves as the primary HR resource for companies ranging from 1 to 15 employees, each at a different stage of building its people infrastructure. It requires autonomy, breadth, comfort with ambiguity, rapid context-switching, and prioritization across organizations. The assignment is approximately five months and is on-site four days per week in Cambridge, Massachusetts. The role reports to the Senior HR Business Partner.

Requirements

At least 5 years of HR generalist and/or business partner experience, ideally supporting multiple business units or startup-stage companies simultaneously.
Strong working knowledge of multi-state employment law and HR compliance requirements.
Prior experience in biotech, life sciences, pharmaceuticals, or fast-growing startup environments.
Experience supporting companies in early stages of HR infrastructure build-out, including settings without handbooks or formal processes.
Ability to operate independently with minimal direction and manage competing priorities across organizations.
Strong command of confidential matters, data-driven decision-making, and interpersonal communication.

Nice To Haves

SHRM-CP/SCP or PHR/SPHR certification.

Responsibilities

Deliver day-to-day HR services across portfolio companies, including onboarding, performance management, employee relations, and offboarding.
Maintain HR records and ensure data integrity across HRIS and other people systems.
Assist with compensation benchmarking, job leveling, and offer structuring as new roles are created.
Coordinate with Talent Acquisition, Payroll, Legal, and Learning & Development to maintain consistency across portfolio companies.
Ensure companies remain compliant with applicable federal, state, and local employment laws, partnering with outside counsel as needed.
Provide general HR administrative support to the Senior HR Business Partner, including scheduling, document management, tracking action items, and coordination across portfolio companies.