Administrative Assistant

We are seeking a proactive, organized, and people-oriented Office Assistant / Receptionist to serve as the face and energy of our office. This role goes beyond traditional reception — it is key to delivering an exceptional first impression to clients and collaborators while ensuring seamless administrative support across teams. 

You will manage front desk operations, coordinate office logistics, and support purchasing and event planning efforts. As the first point of contact your attention to detail, communication skills, and sense of ownership will contribute directly to a positive and efficient work environment.

You will:

• Greet clients, collaborators, and guests with a warm, professional demeanor.
• Manage call routing, messages, and general email correspondence.
• Oversee meeting room schedules and ensure spaces are ready for use.
• Coordinate mail and package deliveries.
• Manage petty cash and basic expense tracking.
• Maintain and organize digital and physical filing systems.
• Assist with invoicing and tracking of purchase orders in the accounting system.
• Support calendar management and office-wide communications.
• Collaborate with the Office Manager and other departments as needed.
• Monitor and maintain inventory of office, cleaning, and cafeteria supplies.
• Assist in purchasing processes and ensure supplier coordination.
• Keep the office environment orderly, stocked, and employee ready.
• Provide logistical support for internal events, workshops, and team activities.
• Act as a liaison with the occupational health and emergency response teams.
• Support internal campaigns that contribute to workplace culture and wellness.

You have:

• 2+ years of experience in administrative or receptionist roles.
• English proficiency: Intermediate to upper-intermediate.
• Experience in events logistics.
• Strong command of MS Office Suite (Word, Excel, Outlook).
• Excellent organizational and multitasking abilities.
• Outstanding interpersonal and communication skills.
• Professional appearance and client-facing demeanor.
• High level of discretion and confidentiality.
• Proactive, problem-solver, and strong team collaborator.

What We Offer:

• Competitive benefits packages
• Vacation, compassionate leave, sick days, and flex days
• Access to online services for families and new parents
• Diversity and Inclusion Board with 12 affinity groups
• Internal learning and development programs
• And more…

At Critical Mass, we value our employees and offer competitive compensation and benefits packages.  If you’re looking for a challenging and rewarding opportunity to make a significant impact on the lives of our employees, we encourage you to apply for this exciting position today!

The Talent Team at Critical Mass is focused on ensuring we provide the best training, onboarding, and employee experience possible! Our new hires & employees are the future of our organization, and we want to set you up for long-term success. In an effort to do so, we expect our team to work from an office a minimum of 3 days a week.

The ask stems from our want to:

Strengthen opportunity for continuous learning
Improve collaboration and team relationships.
Increase employee engagement

This work model balances the need for individual flexibility while maintaining the relentless customer focus we provide at CM. We understand that not everyone may feel comfortable with this expectation, so we ask that you please let us know immediately if there are any concerns so we can help navigate accordingly.

Critical Mass is an equal opportunity employer. 

The Critical Mass Talent Acquisition team will only communicate from email addresses that use the URLs criticalmass.com and us.greenhouse-mail.io. We will not use apps such as Facebook Messenger, WhatsApp, or Google Hangouts for communicating with you. We will never ask you to send us money, technology, or anything else to work for our company. If you believe you are the victim of a scam, please review your local government consumer protections guidance and reach out to them directly.

If U.S. based: https://www.consumer.ftc.gov/articles/job-scams#avoid
If Canada based: https://www.canada.ca/en/services/finance/consumer-affairs.html
If U.K. based: https://www.gov.uk/consumer-protection-rights
If Costa Rica based: https://www.consumo.go.cr/educacion_consumidor/consejos_practicos.aspx