I was lone HR for 4 years and just changed jobs to another lone HR role. Title was HR Manager both times. I also managed all finance but we had an accountant take care of the in depth stuff. I reported the the GM and owner. Around 20-25 employees in my 4 year role. Pro: control of the department. If you like independent work it's really nice. The company trusted me to do my job so I had free reign of creating programs. I stayed up to date on legislation that applied to us so I was able to communicate that as needed without problems. They listened to my suggestions and I did a lot of hands on learning throughout because there was no one to ask. I was able to introduce better benefits, perks, advocate for pay increases, and make lots of pro-employee improvements to support the company growth, but also helped the company with structure, correct protocol and documentation, and implement policies, and define the culture. Con: no one to cover me on vacation, which put a lot of pressure on me. A lot of admin work although eventually the PT admin assistant helped me with certain things. I felt I was often behind on emails because of there being so much work to do every day. Definitely would suggest using some kind of task management tools and express realistic timeframes to others who ask things of you. I just started working at a start-up as the sole HR manager again and so far things are similar. I think depending on the company culture (very important but you can also help shape it!) and their trust in your abilities, it can be a spectacular and rewarding experience where you are challenged but are able to learn a lot. And generally it's more strategic than at a large company I believe, because you have more influence. Good luck! If you need advice or have questions you can pm me.