HR is often ignored in tech startups until things start to break… at which point there’s a scramble to “hire a VP of HR right away.” While this is natural, the reality is that HR is a complex function (like all the other departments), and HR leaders come with a wide variety of skills and seniority. Following is a very simplified way to think about what kind of leader you might need at different stages.

Small companies don’t usually need a dedicated HR function. At this stage, you can often appoint a bright but inexperienced person to help the founders with the day-to-day administration of both HR and Finance activities like benefits, payroll, rent, new hire setup and things like office snacks (if you have an office).

As the company grows past a few dozen employees, some personnel question or issue tends to arise every day, so it helps to have a dedicated HR professional to field these. It’s certainly nice if this person is a “grown up” with some prior HR or management experience, but it can also work to promote a high-performing Office Manager.

At 100 employees, companies tend to shift from solid to liquid state, which means people are constantly joining, leaving and switching roles. It’s now time to have an experienced HR leader who can help bring order and consistency to all this movement. Ideally this person has experience leading HR at a company a bit larger than yours, so they can help guide you for what’s ahead.

After another year or two of torrid growth, organizations get more complex. It’s time to get professional about your compensation systems, titles and org design among other things. I definitely recommend getting someone who’s “been there, done that” if you haven’t already.

For those companies fortunate enough to break out as IPO candidates or other high fliers: congratulations… the world now sees you as a deep-pocketed big company! Now you’ll want the right C-level leader to develop solid management training, thoughtful pathways for promotions and raises, and a deft touch for handling the inevitable sticky situations that arise.