Many real world AI applications involve reasoning on both continuous and discrete variables, while requiring some level of symbolic reasoning that can provide guarantees on the system's behaviour. Unfortunately, most of the existing probabilistic models do not e ciently support hard constraints or they are limited to purely discrete or continuous scenarios. Weighted Model Integration (WMI) is a recent and general formalism that enables probabilistic modeling and inference in hybrid structured domains. A di erence of WMI-based inference algorithms with respect to most alternatives is that probabilities are computed inside a structured support involving both logical and algebraic relationships between variables. While some progress has been made in the last years and the topic is increasingly gaining interest from the community, research in this area is at an early stage. These aspects motivate the study of hybrid and symbolic probabilistic models and the development of scalable inference procedures and e ective learning algorithms in these domains. This PhD Thesis embodies my e ort in studying scalable reasoning and learning techniques in the context of WMI. Now that's almost over, I can say it has been a fun ride. This crazy-fast, colorful journey wouldn't have been the same without the wonderful people I met along the way. Thank you Andrea, thank you Roberto for your kindness and patience in guiding me through these challenging years. Doing a PhD under your supervision has been a life-changing experience and one of the best decisions I've ever made. Life in Trento wouldn't have been as joyful without Marco, Stefano, Dragone, Gianni, Luca, Gianluca and the whole SML family, Edoardo, Zaki, Alessandra, Daniele, Sivam, Genc, Mesay.. I couldn't hope for more supportive and easy-going pals to hang with. I would like to thank Luc, Samuel, Guy, Antonio, Zhe, Fanqi and all the people I met during my visits at KU Leuven and UCLA. Thank you for being so welcoming, working with you was a pleasure and a privilege.