East Potomac Tennis Center has a 10 and under tennis program, and I think that they offer it to the 3-5 set as well. I really like 10 and under tennis - it's geared to them, and my kids seem to really enjoy it.
eastpotomactennis.com

Also, WTEF has a 10 and under program and they have classes as well at Rock Creek Tennis Center. www.wtef.org.

Good Luck!

St. Albans tennis camp starts at 4. Might still have space some weeks this summer.

Sounds good to me, if she's having fun playing I would continue with the lessons or have a parent hit with her regularly but I suspect kids that age do better in a group setting instead of one on one. To start them at an early age is significant in developing skills and confidence in a sport and has lasting effects, but every kid is different and may need some nudging along the way to keep focused.

I have a 4 year old child with an interest and aptitude for tennis, so she's taking lessons at our swim and tennis club. The offerings there are pretty limited, but I'm ignorant about how competitive tennis is played in this area. Assuming this isn't some passing fancy, what are our other options to keep her playing and developing her skills? I feel like I didn't do right by my first kid by recognizing his interests and finding the best opportunities. Hoping I can do better this time around.

I appreciate your advice.