Diversity in tech is about more than gender

It's about a lot of things.
In the context of diversity within tech communities, here are two that I'm not hearing other people talk about: technology discrimination and alcohol.

Do you like my new T-shirts?

It's not about the technology used but what's done with it that counts

If you want to be part of a group of people that are just like you: who have similar experiences, interests, areas of technical focus, and goals, that's okay.
However, I think everyone benefits when a community is open and inviting to people with different backgrounds, interests, skills, and experiences. When there's variety in the room it provides the opportunity for us all to learn new things.

We all benefit when we are exposed to others who are different to us. It makes us better developers and better people.

If you want a community to grow. If you want new people to learn and adopt a technology so it becomes successful that requires that you help new people and make them feel welcome.

You mustn't make fun of people because of the programming language they currently use.
They may have had no say in this. They may be very successful with it and have created many popular, loved, and financially rewarding pieces of software with it. The programming language used to write a piece of software rarely plays a large part in the success or failure of that software. Don't pick on people because they use something that's older than what you use or that you have stopped using.

Do not make fun of people because of the platforms they build tech on.
Again, developers rarely have a say about the platforms they use, particularly in corporate environments. If developers only worked on the latest platforms or used the latest frameworks then the majority of software in the world wouldn't be being maintained or updated. If we want to keep society moving we can't abandon all old software and we can't constantly re-write everything that's in use.

I've seen the numbers. Most developers don't use the latest and greatest technologies or the hottest new language.
If you do, then congratulations. How about sharing your knowledge with others who haven't had that opportunity yet? Help them learn new things. Even if that means you have to help with "older" technologies.

Alcohol and a drinking culture

Not everyone wants to or can drink alcohol. Some people are unable to be around alcohol.
Even if someone who doesn't drink alcohol is in a place where alcohol is served they don't want to be made to feel different or left out.

As a user group organizer, I found people were really positive when we had more than just a small selection of beers to drink. More people were even more positive when I extended the range of soft drinks that were provided. When organizing an evening user group event and providing drinks, I now do one third as a mixture of alcoholic drinks, one third as soft drinks, and one third as fruit juices. Fruit juices were amazingly popular when we first started having them.

When holding evening events in offices or meeting rooms I'd often propose going to a bar afterward. This choice of location was chosen because it was easy and pretty much the only location available. Plus, "it was just what you do." I have the cultural experience where going to a pub to socialize is the norm. However, only a small percentage of people who came to the initial meeting would also come to the pub afterward. There are many reasons for this but I believe the location was one of them. Next time I run an evening event where we can't stay in the meeting venue indefinitely, I'll look harder for alternate locations where we can continue discussions afterward.

I don't drink alcohol. I choose not to based on past experiences and my levels of self-control. Other people don't drink alcohol for other personal or religious reasons.
I'm happy to be in places where alcohol is served and drunk. There are people who are not. Again, this could be for personal, religious, or other reasons. If you host an event involving alcohol it will automatically keep some people away. If an event is about technology, why use something unrelated (alcohol) to keep a large number of potential attendees away.

I've been to a number of events where the presence of alcohol made me (as a non-drinker of alcohol) seem less welcome.

• I was at a conference party with multiple bars serving alcohol. There was only one serving soft drinks. I discovered this as I went round all the bars asking for soft drinks and it was only the last one I came to that had anything. The options were limited and hidden at the back while multiple alcoholic beverages were on display on the counter. The message I took from the conference was that my needs as an attendee were not important.
• I was invited to an event where special, custom, themed, cocktails were being served. This was a tech event and the cocktails were free. I asked what non-alcoholic drinks they had but these were very limited and I had to pay (an unusually large amount) for a coke. The message I took from this was that this was an event for people who drank alcohol. Even though I'd been invited they didn't value me as much as other attendees.
• I once attended a tech event in a bar and the only soft drink they had was coke. I was looked at like there was something wrong with me when I asked if they had any other non-alcoholic drinks. Just drinking cola all night can be unpleasant. Ensure there is more than one non-alcoholic option and don't make people feel uncomfortable if they don't want alcohol.
• I've known tech events where the social aspect was a bar-crawl. Events that encourage lots of drinking (even if that's just implied by visiting lots of different places that serve alcohol) discourage some from attending. 
• I've been at invite-only tech events where the social aspect of the event was beer and spirit tasting. Again, this is actively excluding people from something that was supposed to be tech related.
• I've been to a tech event held in a brewery. A great way to exclude people who can't visit such locations.

I know it's hard to find locations for events. I know it's the norm to do these kinds of events. I know I may seem hypocritical for saying this as I've held events in pubs and bars.
However, if you reward or recognize people in your community with alcohol or events involving alcohol then you make people who don't drink alcohol or actively avoid it less welcome in your community.

If you're a leader or organizer and you want to grow your community (both in numbers and diversity) I hope you'll think about this.

Personally, I'd love to organize and attend more meetups in coffee shops and learn from people who use technologies I don't.