Longwall Top Coal Caving (LTCC) technology has great potential for more efficient mining of Australian thick coal seams. LTCC can potentially double (or greater) the longwall recoverable tonnes, per metre of gateroad development and improve the safety standards in longwall operation. Accurate cavability assessment of the coal seam is the key pre-requisite for successful application of LTCC method. Although some cavability criteria were developed in previous studies, their shortcomings limit their application. Apart from the lack of suitable cavability criterion, the caving principles and mechanisms in longwall operation (and LTCC) is still not well understood. The main objectives of this research work were: 1. to improve the general understanding about the caving mechanisms involved in LTCC operation, 2. to develop a new cavability assessment criterion, and 3. to characterise and classify the caving behaviour in selected Australian longwall operations. For this study a combination of analytical, observational and empirical engineering methods were used to reduce the shortcoming of individual design methods. For analytical study, the Distinct Element Method (DEM) was selected for computational analysis as the most suitable technique for this type of study. For observational methods, the size distribution of particles in goaf was used as a monitoring measure for caving performance evaluation and this method was performed in three Australian longwall operations (Ulan, West Wallsend and Broadmeadow). The Empirical assessment was performed by using the results of observational/computational analyses along with basic geological/geotechnical data from selected mine sites to back analyse and re-evaluate the results. The most significant outcomes of this study include: 1. a new cavability assessment system (Top Coal Cavability Rating, TCCR) that was developed based on computational analysis and by back analysis of past LTCC experience in China, 2. Improved understanding of caving mechanism, deformation mechanism and drawing mechanism of top coal in LTCC method, 3. advanced numerical models (UDEC, 3DEC and PFC models) that not only can be used for future research but can also be employed for LTCC design purposes, 4. characterisation and classification of caving behaviour in three Australian longwall operations. The results of this study can be effectively used by Australian coal industry in feasibility and design studies of LTCC operation. The new cavability criterion can be used to identify and quantify the major risks that may be involved in LTCC application.