Analysing Gaelic Footballers’ training load is important, as optimal levels of training will improve sporting performance and physical well-being. However, excessive training could increase the likelihood of injury or overtraining. Aim: To develop an effective and valid method of assessing training load in Gaelic Footballers. Methods: The primary aim was achieved through the completion of four related studies. Study One: The Training Diary was developed and a pilot study was completed. Study Two: The paper and online Training Diary’s efficacy was compared over six Gaelic Football teams of both genders aged 14-30. Study Three: The Training Diary was validated against an accelerometer, SenseCam and interview. Study Four: The effect of an email and text reminder on the Training Diary was assessed. Results: The Training Diary had a high face and convergent validity against the objective methods of measurement. The average response rate for the paper, online, email and text protocols was 26.6%, 15.2%, 21.9% and 31.9% respectively. No significant difference was found between print, online, email and text protocols (p>0.05). There was a moderate significant difference between the online Training Diary and a text reminder (p<0.05). Gender caused no significant effect on response rates in the online, email and text protocols. However, the paper Training Diary noted a large effect (t(4) =-4.08,p<0.05,two-tailed). The under 14, minor and adult teams significantly differed with each other in the Online Training Diary. A significant difference was found between the under 14 and minor team using the text reminder. No significant preference was found between the paper and online Training Diary in the questionnaire (p>0.05). Reminders, especially the text reminder were found to be statistically helpful (p<0.05). Conclusion: Training Diaries are an extremely valid and reasonably effective method of assessing training load in Gaelic Footballers. Reminders assist in increasing the response rate.