When I was a partner at Y Combinator, the most common late-night emails from founders weren’t about product-market fit or fundraising – they were about partner problems. What’s fascinating is that most of these issues could have been avoided with proper vetting. Through our work at Do Not Work With (DNWW.io), we’ve gathered insights from thousands of partnership situations. Let me share what actually works when evaluating potential business partners.
The Real Vetting Process
Forget what you’ve read in most business books. Real partner vetting isn’t about personality tests or formal interviews. It’s about seeing how someone operates under various conditions over time. Here’s what actually matters.
Work Together Before You Commit
The single best predictor of partnership success is real work experience together. One YC founder avoided a disastrous partnership by doing a two-week trial project with their potential co-founder. During this time, they discovered fundamental differences in their work styles and decision-making approaches. This saved them from what could have been years of conflict.
Build a project together. It doesn’t need to be your main idea – in fact, it’s better if it’s not. Work on something small but real. Watch for:
- How they handle disagreement: Do they get defensive or stay solution-focused?
- Their work patterns: Are they consistent? Do they communicate clearly?
- Decision-making style: Do they make decisions based on data or gut? How do they handle uncertainty?
- Response to stress: What happens when things don’t go as planned?
Understand Their Real Motivations
People will tell you what they think you want to hear. Instead of asking why they want to be your partner, watch what they do when no one’s looking. A founder in our network spotted a red flag when their potential partner spent more time negotiating equity than discussing product vision. Their motivations became clear through their actions, not their words.
The Money Test
Have detailed discussions about money early. Not just about equity splits, but about salary expectations, spending habits, and financial priorities. One YC company fell apart because the founders had drastically different views on how to handle early revenue – one wanted to reinvest everything, the other needed immediate income.
Watch especially for:
- Financial pressure points: What are their immediate needs and obligations?
- Risk tolerance: How do they think about salary versus equity?
- Spending philosophy: Are they conservative or aggressive with resources?
- Long-term expectations: What’s their timeline for personal financial goals?
Reference Checks That Actually Work
Standard reference checks are nearly useless – you’ll only hear what they want you to hear. Instead, use the “spider web” method: Start with their given references, then ask each reference for two more people who’ve worked with your potential partner. The real insights come from these second and third-degree connections.
When talking to references, don’t ask general questions. Ask about specific situations:
- “How did they handle a major disagreement?”
- “What happened when the team missed a critical deadline?”
- “How did they react to receiving difficult feedback?”
- “Tell me about a time they had to admit they were wrong.”
The Pressure Test
Create situations that reveal how they handle stress. One effective YC founder deliberately scheduled meetings early in the morning and late in the evening to see how their potential partner handled unexpected demands. Another introduced artificial obstacles into their trial project to observe stress responses.
Values Alignment Check
Values misalignment kills more partnerships than competency issues. Don’t just discuss values – test them. Present real scenarios and watch how they react:
- “A customer is willing to pay double if we compromise on privacy. What do we do?”
- “We can close a round faster if we hide this quarter’s downturn. Thoughts?”
- “A key employee made a mistake that cost us money. How do we handle it?”
The Three-Month Rule
If possible, structure your partnership to have a three-month trial period. Make it clear that either party can walk away, no hard feelings. This creates space for both sides to evaluate the fit honestly. Several YC companies have saved themselves years of pain by implementing this simple practice.
Using Data Effectively
Check DNWW.io and other sources for any history of partnership issues. But remember – lack of negative information isn’t the same as positive verification. One founder found nothing negative about their potential partner online, but also noticed they had no long-term professional relationships – a subtle but important red flag.
The Communication Test
Pay attention to their communication patterns during the vetting process. Do they:
- Respond promptly to messages?
- Follow through on small commitments?
- Provide clear updates without prompting?
- Handle misunderstandings directly?
Dealing with Bad Partners
If you realize you have the wrong partner, act quickly. The cost of a bad partnership compounds over time. A YC company once spent 18 months trying to make a poor partnership work – they could have saved the company by acting on their early concerns.
A Framework for Partner Evaluation
Think of partner vetting as progressive exposure:
- Start with basic information verification
- Move to structured work experiences
- Introduce stress tests
- Check alignment through real scenarios
- Verify through deep reference checks
- Trial period with clear expectations
Final Thoughts
Remember: Your choice of partner will impact every future decision your company makes. Take the time to get it right. And if you see red flags, don’t rationalize them away. They usually turn into the reasons partnerships fail.
The best partnerships aren’t formed in excitement over shared opportunities – they’re forged through careful evaluation and proven alignment. Do the work upfront, and you’ll save yourself years of potential pain.