Supervisor's Foreword; Preface; Thesis Outline; Acknowledgements; Contents; 1 Introduction; 1.1 The Current Paradigm of the Star Formation Process; 1.1.1 The Interstellar Medium (ISM); 1.1.2 Molecular Clouds ; 1.1.3 Turbulence and Magnetism in Molecular Clouds ; 1.1.4 Filamentary Structure ; 1.2 Physical Properties of Starless and Prestellar Cores; 1.2.1 Temperature ; 1.2.2 Mass ; 1.2.3 Magnetic Fields ; 1.2.4 External Pressure ; 1.2.5 Morphology; 1.2.6 Environment ; 1.3 Stability of Starless and Prestellar Cores ; 1.3.1 The Jeans Mass; 1.3.2 The Virial Theorem

1.3.3 Bonnor-Ebert Stability Criterion 1.4 Evolution and Lifetime of Starless Cores; 1.5 The Initial Mass Function; 1.6 Protostars; 1.6.1 Class 0 ; 1.6.2 Class I ; 1.6.3 Flat ; 1.6.4 Class II ; 1.6.5 Class III ; 1.7 The Gould Belt ; 1.7.1 JCMT Gould Belt Legacy Survey ; 1.7.2 Herschel Gould Belt Survey ; 1.8 Summary; References; 2 Instrumentation; 2.1 The James Clerk Maxwell Telescope; 2.1.1 SCUBA-2; 2.1.2 SCUBA-2 Data Reduction; 2.1.3 HARP-B and ACSIS; 2.1.4 Carbon Monoxide Contamination of SCUBA-2 Data; 2.2 The Herschel Space Observatory; 2.2.1 SPIRE Data Reduction

2.2.2 PACS Data Reduction2.2.3 Absolute Calibration of Herschel Data; 2.3 IRAM 30m Telescope; 2.4 SCUBA-2 and Herschel Compatibility; 2.4.1 Spatial Filtering; 2.4.2 Common-Resolution Convolution Kernels; 2.5 Summary; References; 3 The Ophiuchus Molecular Cloud; 3.1 Introduction; 3.2 Observations; 3.2.1 SCUBA-2; 3.2.2 HARP; 3.2.3 Herschel; 3.2.4 IRAM; 3.3 Data Processing; 3.3.1 CO Contamination; 3.3.2 Spatial Filtering; 3.4 Results; 3.4.1 Source Extraction; 3.4.2 Source Completeness; 3.4.3 Source Characterisation from Continuum Data; 3.4.4 Source Mass Distribution

3.4.5 Source Characterisation from Spectral Data3.5 Energy Balance and Stability; 3.5.1 Gravitational and Internal Energy; 3.5.2 External Gas Pressure; 3.5.3 External Pressure from Ionising Photons; 3.5.4 Magnetic Energy Density; 3.5.5 Core Stability; 3.5.6 Bonnor-Ebert Critical Mass; 3.6 Regional Variations in Core Properties; 3.6.1 Oph A; 3.6.2 Oph A; 3.6.3 Oph B; 3.6.4 Oph B-11; 3.6.5 Oph C; 3.6.6 Oph E and F; 3.6.7 L1689 and L1709; 3.6.8 Gradients Across the Cloud; 3.7 Summary; References; 4 The Taurus Molecular Cloud; 4.1 Introduction; 4.2 Observations; 4.2.1 SCUBA-2

4.2.2 Herschel Space Observatory4.3 Results; 4.3.1 Source Extraction; 4.3.2 Source Characterisation; 4.4 Discussion; 4.5 Energy Balance and Stability; 4.5.1 Gravitational Potential Energy; 4.5.2 Internal Energy; 4.5.3 External Pressure Energy; 4.5.4 Magnetic Energy Density; 4.5.5 Virial Balance; 4.5.6 13CO Virial Analysis; 4.5.7 Bonnor-Ebert Stability; 4.5.8 Regional Variations; 4.6 Summary; References; 5 The Cepheus Flare; 5.1 Introduction; 5.2 Observations; 5.3 Results; 5.3.1 Cepheus Flare Region; 5.3.2 Source Extraction; 5.3.3 Source Characterisation; 5.4 Discussion of Derived Properties