If The Ethical Slut was the first joyful permission slip and More Than Two was the philosophical manifesto, Tristan Taormino’s Opening Up (2008) is the practical field guide. Think of it as the Lonely Planet for non-monogamy: a map of the many different ways people actually live and breathe it.

What It’s About

Opening Up is structured around real-world case studies. Taormino interviewed dozens of people in open relationships — swingers, polycules, BDSM practitioners, triads, solo poly folks, you name it — and wove their stories into a manual.

The book covers:

• Relationship styles. From hierarchical polyamory to casual swinging, and everything in between.
• Agreements and rules. How people set them, how they evolve, and what happens when they break.
• Common challenges. Jealousy, time management, sexual health, disclosure to family, parenting.
• Community wisdom. What works, what doesn’t, and what “open” looks like across cultures and subcultures.

Strengths

• Wide scope. Instead of prescribing a single model, Opening Up gives you a buffet. It’s the book you read when you want to see what’s possible.
• Story-driven. The case studies make it lively and human. You’re not just reading theory, you’re peeking into real bedrooms and living rooms.
• Practicality. Taormino doesn’t shy away from messy stuff like STI testing, managing calendars, or coming out to parents.

Weaknesses

• Less depth. Because it covers so many different styles, it sometimes skims the surface. You won’t get the deep dive into autonomy (More Than Two) or attachment (Polysecure).
• Dated examples. Published in 2008, some of the cultural context (language, gender discussions, even STI framing) feels behind today’s discourse.
• Rule-heavy bias. The book sometimes leans toward structured agreements and rules, which might not resonate for folks who prefer relationship anarchy or less hierarchical frameworks.

Why It Still Matters

Opening Up is the most approachable entry point for someone curious but uncertain. If you’ve ever thought, “Okay, but what does it actually look like to live this way?” this book answers it with a chorus of voices. It’s also one of the few ENM books that doesn’t assume you’re starting from polyamory — it validates swinging, casual non-monogamy, and kink-based arrangements as equally legitimate.

It may not be as radical as The Ethical Slut or as cerebral as Polysecure, but it fills a crucial role: showing the sheer diversity of open relationships and normalising them through story.